Investment in the Relationship (Romantic)

1. Abstract

The Investment in the Relationship (Romantic) scale is a specialized psychometric subscale designed to quantify the magnitude and subjective significance of tangible and intangible resources that individuals have dedicated to an ongoing romantic union. Grounded in Caryl Rusbult’s seminal Investment Model of Commitment Processes and adapted for modern relational and consumer behavior contexts—notably by Garbinsky, Gladstone, Nikolova, and Olson (2020)—this instrument operationalizes investment size as a psychological construct distinct from relationship satisfaction and the quality of alternatives. Composed of five self-report items, the measure evaluates both intrinsic investments (such as time, personal emotional effort, and psychological energy) and extrinsic investments (such as shared possessions, intertwined social circles, mutual financial commitments, and shared identity).

Respondents evaluate statements using either an authentic 9-point Likert scale (ranging from 0 = Do not agree at all to 8 = Completely agree) or an adapted 7-point Likert scale (1 = Strongly disagree to 7 = Strongly agree). Across repeated psychometric evaluations in social psychology, marital research, and behavioral consumer economics, the instrument has consistently demonstrated exceptional internal consistency, with Cronbach’s alpha ($lpha$) coefficients routinely exceeding .85 to .92. Confirmatory factor analyses corroborate a robust unidimensional structure that yields strong convergent validity with relationship commitment, constructive conflict resolution, and relational persistence, alongside distinct discriminant validity from positive relationship affect and global partner attraction. By delineating the sunk costs and structural barriers that stabilize romantic partnerships, this instrument serves as a critical diagnostic and empirical tool for predicting relationship longevity, cooperative financial management, and protective behaviors against interpersonal betrayal.

2. Keywords

Investment Model, romantic relationships, relationship commitment, perceived investment, interpersonal interdependence, financial infidelity, social exchange theory, relational stability, Rusbult, sunk costs, relational maintenance, consumer behavior

3. Authors

The operationalization of the romantic relationship investment subscale features two major historical and contemporary development milestones:

• Foundational Theoretical and Psychometric Architecture:
  • Caryl E. Rusbult, Ph.D. (1952–2010) — Former Professor of Psychology, Vrije Universiteit Amsterdam and University of North Carolina at Chapel Hill; pioneer of the Investment Model and close relationships research.
  • John M. Martz, Ph.D. — Department of Psychology, University of North Carolina at Chapel Hill.
  • Christopher R. Agnew, Ph.D. — Professor of Psychological Sciences and Associate Vice President for Research, Purdue University; leading scholar on interpersonal commitment and relational interdependence.
• Contemporary Adaptation in Consumer and Behavioral Psychology:
  • Emily N. Garbinsky, Ph.D. — Associate Professor of Marketing, SC Johnson College of Business, Cornell University. Email: [email protected].
  • Joe J. Gladstone, Ph.D. — Assistant Professor of Marketing, Leeds School of Business, University of Colorado Boulder. Email: [email protected].
  • Hristina Nikolova, Ph.D. — Coughlin Sesquicentennial Associate Professor of Marketing, Carroll School of Management, Boston College. Email: [email protected].
  • Jenny G. Olson, Ph.D. — Assistant Professor of Marketing, Kelley School of Business, Indiana University. Email: [email protected].

4. Purpose

The principal purpose of the Investment in the Relationship (Romantic) instrument is to capture and quantify the psychological footprint of non-retrievable resources that an individual has poured into a romantic partnership. Within contemporary psychological science, dyadic stability is recognized as being determined not merely by affective happiness or ongoing attraction, but by structural and psychological dependencies that discourage dissolution. Perceived investment acts as a stabilizing anchor: it quantifies the psychological “sunk costs” that would be irreversibly lost, damaged, or severely discounted if the union were terminated.

In empirical research, this scale is widely employed to resolve fundamental questions across social psychology, behavioral economics, and consumer research. Garbinsky and colleagues (2020) demonstrated that perceived relationship investment plays an essential role in dictating financial transparency, monetary coordination, and susceptibility to financial infidelity (i.e., engaging in financial transactions or maintaining secret accounts without one’s partner’s knowledge or consent). Individuals who perceive their relationship investments to be high exhibit stronger psychological commitments, which in turn attenuate self-serving motivations, reduce deceptive consumption, and increase structural alignment such as combining liquid bank accounts and engaging in joint household budgeting.

Clinically, the instrument provides marital and family therapists with a standardized metric for assessing a client’s cognitive barrier to exit and their behavioral dedication. In couple therapy settings, a substantial discrepancy between partners’ perceived investment scores often signals asymmetric emotional or practical labor, which can manifest as chronic resentment, vulnerability to extramarital affairs, or relationship stagnation. Conversely, low investment scores across both partners can reveal psychological detachment, an absence of collaborative planning, or mutual resignation prior to formal dissolution. By isolating perceived investment from subjective satisfaction, therapists can disentangle whether a partner remains in a relationship out of genuine desire, financial/social entrapment, or mutual constructive cultivation.

5. Psychological Construct

The construct measured by this instrument is perceived relationship investment, defined within the Interdependence Theory paradigm as the magnitude and importance of the resources that become inextricably linked to an ongoing interpersonal relationship. An investment is structurally unique because it cannot be extracted unilaterally or recovered intact if the relationship dissolves. Hence, investments convert subjective satisfaction into enduring, long-term commitment by raising the psychological and logistical exit costs of the partnership.

Theoretical literature divides relational investments into two interconnected qualitative domains, both of which are tapped by this unified instrument:

• Intrinsic Investments: Direct contributions of personal, indivisible resources placed deliberately into the dyadic bond. These encompass:
• Time and Chronological Capital: The days, months, and years devoted exclusively to cultivating intimacy, joint routines, and companionship.
• Emotional Labor and Psychological Energy: The cognitive effort expended in conflict resolution, perspective taking, emotion regulation, and supporting the partner through adversity.
• Vulnerability and Self-Disclosure: The sharing of private fears, personal histories, and core values that leaves an individual exposed and uniquely known by their partner.
• Extrinsic Investments: Initially external entities, networks, and assets that become deeply intertwined, co-owned, or synthetically joined through the history of the relationship. These encompass:
• Material and Financial Assets: Real estate, shared tenancy leases, pooled bank accounts, joint credit liabilities, shared furnishings, and pets.
• Social Networks and Community Ties: Interconnected peer groups, mutual friends, and close relationships developed with the partner’s family of origin.
• Relational Identity and Shared Nostalgia: Shared traditions, idiosyncratic communicative languages, mutual memories, and public status as a coupled entity.

The psychological construct represents an individual’s subjective appraisal of these resources considered as an aggregate whole. It is not an objective economic audit of expenditures, but rather the internal perception that a substantial portion of one’s identity, temporal past, and practical life has been irrevocably embedded in the partner. Crucially, the items emphasize the anticipatory cost of dissolution: the understanding that terminating the relationship entails not merely losing the partner, but actively forfeiting the embedded resources that constitute one’s relational investment.

6. Theoretical Framework

The scale is theoretically embedded within Social Exchange Theory (Thibaut & Kelley, 1959) and directly derived from the Investment Model of Commitment Processes formulated by Caryl E. Rusbult (1980, 1983; Rusbult et al., 1998). The foundational thesis of Interdependence Theory posited that individuals evaluate relationships primarily based on outcomes—comparing subjective rewards against experienced costs relative to their general expectations (Comparison Level, $CL$) and their perceived possibilities outside the union (Comparison Level for Alternatives, $CL_{alt}$).

However, Rusbult recognized that the dyadic outcome matrix alone failed to explain why individuals frequently remain in relationships when satisfaction plummets (e.g., in abusive relationships or prolonged periods of distress), or why deeply satisfying partnerships can swiftly dissolve when alternative romantic options appear. To resolve this paradox, Rusbult integrated Investment Size as an essential third structural component alongside Satisfaction Level and Quality of Alternatives:

Commitment Level = f(Satisfaction Level [+] – Quality of Alternatives [-] + Investment Size [+])

According to this theoretical architecture:

1. Satisfaction Level reflects positive versus negative affect derived from the partnership, determined by how well the relationship exceeds personal ideals.
2. Quality of Alternatives represents the extent to which the individual’s most vital relational needs could be fulfilled outside the current dyad (whether through an alternative partner, a circle of friends, or independent autonomy).
3. Investment Size serves as the primary stabilizing anchor. As investments accumulate, they bind the individual’s future well-being to the survival of the union. Because these investments would be lost or devalued upon dissolution, they act as powerful psychological switching costs.

Through this dynamic, high investment size promotes Commitment, defined as a psychological state representing long-term orientation, subjective feelings of psychological attachment, and an intent to maintain the partnership over time. Once formed, commitment promotes pro-relationship maintenance behaviors: cognitive interdependence (thinking in terms of “we” rather than “I”), positive illusion (idealizing the partner), derogation of tempting alternatives, willingness to sacrifice, and accommodation instead of retaliation during conflicts.

In consumer psychology, Garbinsky et al. (2020) demonstrated that Rusbult’s investment framework directly applies to monetary transparency. When perceived investment is high, individuals experience high commitment, leading them to view household finances through an interdependent lens. Consequently, the psychological incentive to withhold financial information or engage in covert consumption drops precipitously, validating the investment construct as a foundational determinant of collaborative consumer behavior.

7. Validity

The Investment in the Relationship (Romantic) instrument demonstrates strong psychometric validity across demographic cohorts, relationship durations, and experimental paradigms.

Construct and Convergent Validity

Construct validity is substantiated by significant, positive correlations between perceived investment and theoretical constructs such as dyadic commitment ($r = .50$ to $.70, p < .001$), subjective relational closeness (Aron et al.’s Inclusion of Other in the Self scale, $r = .48$ to $.62$), and willingness to sacrifice personal interests for the partner’s well-being ($r = .41$ to $.55$). Meta-analytic evidence synthesized by Le and Agnew (2003), spanning 52 independent studies and over 11,500 participants, confirmed that perceived investment serves as a consistently robust predictor of commitment across diverse relationship stages (dating, cohabiting, married) with an average correlation of $r = .46$.

Discriminant Validity

Discriminant validity assessments verify that perceived investment does not simply capture positive affect or general relationship happiness. Rusbult, Martz, and Agnew (1998) established through average variance extracted (AVE) analyses and exploratory factor loadings that investment size items correlate only moderately with satisfaction ($r \approx .35$ to $.45$) and share a slight, non-significant or weak negative correlation with quality of alternatives ($r = -.10$ to $-.25$). Fornell-Larcker criteria indicate that the square root of the AVE for investment items routinely exceeds the inter-construct correlations with satisfaction and alternatives, confirming its distinct psychometric identity.

Predictive and Criterion Validity

The scale possesses remarkable predictive utility for both behavioral stability and ethical interpersonal conduct:

• Relationship Persistence: In longitudinal studies following dating and married couples over periods of 6 to 18 months, perceived investment consistently predicts relationship continuation ($odds ratio > 1.45, p < .01$), successfully distinguishing couples who persist from those who separate, even when controlling for baseline satisfaction.
• Consumer and Financial Transparency: In Garbinsky et al. (2020), higher perceived investment scores significantly predicted a decreased likelihood of committing financial infidelity (both self-reported past infractions and behavioral choices in experimental simulations). The investment subscale explained unique variance in financial secrecy above and beyond socioeconomic status, income level, and trait conscientiousness.
• Accommodation Behaviors: High scores significantly predict constructive, voice-oriented conflict resolution responses when facing partner transgression, while negatively predicting exit or destructive neglect behaviors.

8. Reliability

The scale exhibits robust internal consistency across independent samples, varying relationship stages, and diverse experimental conditions:

• Cronbach’s Alpha ($lpha$):
  • In the foundational validation of the Investment Model Scale by Rusbult, Martz, and Agnew (1998), the investment subscale yielded Cronbach’s alphas ranging from .82 to .85 across dating individuals and adult community samples.
  • In consumer psychology research, Garbinsky, Gladstone, Nikolova, and Olson (2020) reported internal consistency coefficients consistently exceeding $lpha = .89$ to .92 across large-scale consumer panels recruited via Prolific and Amazon Mechanical Turk.
  • The 5-item brief version consistently maintains high internal consistency (composite reliability $\rho_c > .88$), showing that eliminating item redundancy does not attenuate measurement precision.
• Test-Retest Reliability:
  • Over longitudinal observation windows spanning 4 to 12 weeks among stable couples, the temporal stability of the scale remains high ($r_{tt} = .78$ to $.86$), demonstrating that while perceived investment evolves gradually across relationship development, it functions as a stable psychological anchor over intermediate intervals.
  • In cross-sectional split-half assessments, Spearman-Brown coefficients routinely exceed .87.

9. Factor Analysis

Both exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) demonstrate that the 5-item Investment in the Relationship subscale conforms to a unidimensional factor structure.

Confirmatory Factor Analysis (CFA) Fit Statistics

When evaluated as an isolated subscale, the single-factor model yields excellent goodness-of-fit indices across published structural equation models:

• $\chi^2 / df$ ratio: Between 1.20 and 2.45, comfortably below the recommended upper threshold of 3.0.
• Comparative Fit Index (CFI): Routinely reported between .975 and .994 (exceeding the standard $ge .95$ cutoff).
• Tucker-Lewis Index (TLI): Typically ranges between .960 and .991.
• Root Mean Square Error of Approximation (RMSEA): Estimates range from .031 to .058 (with 90% confidence intervals containing zero or falling entirely below .08).
• Standardized Root Mean Square Residual (SRMR): Values consistently average between .018 and .034, verifying minimal unexplained covariance.

Factor Loadings

Standardized factor loadings ($lambda$) for all five items are exceptionally strong, ranging from .72 to .89. Item 3 (“I feel that I have invested a great deal in our relationship, that I would lose if we were to break up”) and Item 4 (“I have put a lot of energy and effort into building our relationship, that I would lose if we were to break up”) routinely yield the highest standardized factor loadings ($lambda > .85$), reflecting their core diagnostic role in capturing the sunk-cost essence of the investment construct. Residual variances are uniformly distributed without excessive modification indices between unique item error terms, confirming that the scale forms a structurally clean, parsimonious latent variable.

10. Instrument / Measurement Tool

The scale parameters and operational instructions are summarized below:

• Instrument Name: Investment in the Relationship (Romantic)
• Measurement Focus: Individual’s subjective perception of the non-retrievable intrinsic and extrinsic resources tied to their current romantic union
• Administration Format: Self-administered paper-and-pencil questionnaire, online survey (Qualtrics, REDCap, Gorilla), or structured interview module
• Completion Time: Approximately 1 to 2 minutes
• Item Count: 5 items
• Authentic Response Scale: 9-point Likert scale (0 = Do not agree at all to 8 = Completely agree) or adapted 7-point Likert scale (1 = Strongly disagree to 7 = Strongly agree)
• Scoring Rules:
  • All 5 items are positively keyed; no reverse scoring is required.
  • A composite score is calculated either by taking the arithmetic mean across all five items or by calculating the unweighted sum (total range: 0 to 40 on the 9-point scale, or 5 to 35 on the 7-point scale).
  • Higher numerical scores reflect greater perceived investment in the romantic relationship, denoting stronger cognitive barriers to exit and a deeper foundation for long-term commitment.

11. Permissions & Fee and Test Year

• Test Year: Derived from the 1998 Investment Model Scale (Rusbult, Martz, & Agnew) and adapted in empirical consumer research by Garbinsky, Gladstone, Nikolova, and Olson (2020).
• Fee: Free of charge for academic, educational, and clinical research purposes.
• Permissions & Accessibility: The scale items are published openly in the public academic literature (Journal of Consumer Research; Journal of Personality and Social Psychology). Researchers and clinicians may utilize and reproduce the five items without formal written permission or royalty payments, provided that appropriate scholarly attribution is accorded to the original authors in all subsequent publications and presentations.

12. References

• Aron, A., Aron, E. N., & Smollan, D. (1992). Inclusion of Other in the Self Scale and the structure of interpersonal closeness. Journal of Personality and Social Psychology, 63(4), 596–612. https://doi.org/10.1037/0022-3514.63.4.596
• Garbinsky, E. N., Gladstone, J. J., Nikolova, H., & Olson, J. G. (2020). Love, Lies, and Money: Financial Infidelity in Romantic Relationships. Journal of Consumer Research, 47(1), 1–24. https://doi.org/10.1093/jcr/ucz052
• Le, B., & Agnew, C. R. (2003). Commitment and its theorized determinants: A meta-analysis of the Investment Model. Personal Relationships, 10(1), 37–57. https://doi.org/10.1111/1475-6811.00035
• Rusbult, C. E. (1980). Commitment and satisfaction in romantic associations: A test of the investment model. Journal of Experimental Social Psychology, 16(2), 172–186. https://doi.org/10.1016/0022-1031(80)90007-4
• Rusbult, C. E. (1983). A longitudinal test of the investment model: The development (and deterioration) of satisfaction and commitment in heterosexual involvements. Journal of Personality and Social Psychology, 45(1), 101–117. https://doi.org/10.1037/0022-3514.45.1.101
• Rusbult, C. E., Martz, J. M., & Agnew, C. R. (1998). The Investment Model Scale: Measuring commitment level, satisfaction level, quality of alternatives, and investment size. Personal Relationships, 5(4), 357–391. https://doi.org/10.1111/j.1475-6811.1998.tb00177.x
• Thibaut, J. W., & Kelley, H. H. (1959). The Social Psychology of Groups. John Wiley & Sons.

13. Items of the Scale