Introduction: Infidelity is a breach of trust or a crossing of the boundaries of the primary relationship and it influences intimate relationships. It can be categorised as either sexual or emotional infidelity. In Portugal, there have been few studies on this subject using suitable instruments. Objective: This study aimed to analyse the factor structure, psychometric properties, and gender invariance of the Infidelity Scale (IS) in Portuguese adults. Method: The sample comprised 660 Portuguese adults (455 women and 205 men) between 18 and 79 years of age who had been unfaithful in their relationships. Results: The confirmatory analysis showed a structure with two factors (sexual and emotional infidelity), and good values for convergent and discriminant validity were found. The results displayed a satisfactory model fit and the non-invariance of the factor structure between women and men. Conclusion: This is the first Portuguese version of the IS, an instrument for the study of intimate relationships which contributes to the development of multicultural research.

---

Keywords:
Infidelity Scale, relationship, assessment, gender

03_RSP_29(2)_22023_Infidelity_Almeida

Almeida, T. C., Fernandes, R. M., & Cunha, O. (in press). Brief measure of affective lability among Portuguese community and justice samples: Psychometrics and measurement invariance. Crime & Delinquency.

APA (2017). Association’s (APA) ethical principles of psychologists and code of conduct. American Psychology Association.

Apostolou, M., Constantinou, C., & Anagnostopoulos, S. (2019). Reasons that could lead people to divorce in an evolutionary perspective: Evidence from Cyprus. Journal of Divorce & Remarriage, 60(1), 27-46. https://doi.org/10.1080/10502556.2018.1469333

Arantes, J., Barros, F., & Oliveira H. (2020). Extradyadic behaviors and gender: How do they relate with sexual desire, relationship quality, and attractiveness. Frontiers in Psychology, 10(2554), 1-12. https://doi.org/10.3389/fpsyg.2019.02554

Ashdown, B. K., Hackathorn, J. M., & Daniels, J. (2019). Scandalous: Christian identification, sex guilt, and the mediated demonization of the participants in the AshleyMadison scandal. The Journal of Social Psychology, 159(3), 244-256. https://doi.org/10.1080/00224545.2018.1461603

Barta, W., & Kiene, S. (2005). Motivations for infidelity in heterosexual dating couples: The roles of gender, personality differences, and sociosexual orientation. Journal of Social and Personal Relationships, 22(3), 339-360. https://doi.org/10.1177/0265407505052440

Beaton, D. E., Bombardier, C., Guillemin, F., & Ferraz, M. B. (2000). Guidelines for the process of cross-cultural adaptation of self-report measures. Spine, 25(24), 3186-3191. https://doi.org/10.1097/00007632-200012150-00014

Beltrán-Morillas, A. M., Alonso-Ferres, M., Garrido-Macías, M., Villanueva-Moya, L., Sánchez-Hernández, M. D., & Expósito, F. (2022). The relationship between the motivation to commit infidelity and negative affect and self-esteem: How cheating in romance might signal positive well-being in adolescents. Psychological Reports, 125(1), 517-544. https://doi.org/10.1177/0033294120973947

Blow, A., & Hartnett, K. (2005). Infidelity in committed relationships: A methodological review. Journal of Marital and Family Therapy, 31(2), 183-216. https://doi.org/10.1111/j.1752-0606.2005.tb01555.x

Brand, R., Markey, C., Mills, A., & Hodges, S. (2007). Sex differences in self-reported infidelity and its correlates. Sex Roles, 57, 101-109. https://doi.org/10.1007/s11199-007-9221-5

Buss, D. M. (2018). Sexual and emotional infidelity: Evolved gender differences in jealousy prove robust and replicable. Perspectives on Psychological Science, 13(2) 155-160. https://doi.org/10.1177/1745691617698225

Canto, J. M., Alvaro, J. L., Pereira, C., Garrido, A., Torres, A. R., & Pereira, M. E. (2017). Jealousy, gender, and culture of honor: A study in Portugal and Brazil. The Journal of Psychology, 151(6), 580-596. https://doi.org/10.1080/00223980.2017.1372344

Cheung, G. W., & Rensvold, R. B. (2002). Evaluating goodness-of-fit indexes for testing measurement invariance. Structural Equation Modeling, 9(2), 233–255. https://doi.org/10.1207/S15328007SEM0902_5

Domingues, A. F., Marques, M. V., & Simões, S. C. (2017). Estudo preliminar de adaptação e validação da Escala de Tolerância à Infidelidade. Revista Portuguesa De Investigação Comportamental e Social, 3(1), 27-40. https://doi.org/10.7342/ismt.rpics.2017.3.1.46

Drigotas, S., Saftrom, A., & Gentilia, T. (1999). An investment model prediction of dating infidelity. Journal of Personality and Social Psychology, 77(3), 509-524. https://doi.org/10.1037/0022-3514.77.3.509

Fife, S. T., Theobald, A. C., Gossner, J. D., Yakum, B. N., & White, K. L. (2022). Individual healing from infidelity and breakup for emerging adults: A grounded theory. Journal of Social and Personal Relationships, 39(6), 1814-1838. https://doi.org/10.1177/02654075211067441

Fincham, F. D., & May, R. W. (2017). Infidelity in romantic relationships. The Current Opinion in Psychology, 13, 70–74. https://doi.org/10.1016/j.copsyc.2016.03.008

Finn, M. (2012). Monogamous order and the avoidance of chaotic excess. Psychology and Sexuality, 3(2), 123–136. https://doi.org/10.1080/19419899.2011.551834

Fish, J., Pavkov, T., Wetchler, J., & Berrick, J. (2012). Characteristics of those who participate in infidelity: The role of adult attachment and differentiation in extradyadic experiences. The American Journal of Family Therapy, 40, 214-229. https://doi.org/10.1080/01926187.2011.601192

Gomez, R., & Leal. I. (2008). Ajustamento conjugal: Características psicométricas da versão portuguesa da Dyadic Adjustment Scale [Marital adjustment: Psychometric characteristics of the Portuguese version of the Dyadic Adjustment Scale]. Análise Psicológica, 4, 625-638. https://doi.org/10.14417/ap.522

González-Rivera, J., Aquino-Serrano, F., & Pérez-Torres, E. (2020). Relationship satisfaction and infidelity-related behaviors on social networks: A preliminary online study of Hispanic women. Investigation in Health, Psychology, and Education, 10(1), 297-307. https://doi.org/10.3390/ejihpe10010023

Guitar, A. E., Geher, G., Kruger, D. J., Garcia, J. R., Fisher, M. L., & Fitzgerald, C. J. (2017). Defining and distinguishing sexual and emotional infidelity. Current Psychology, 36(3), 434–446. https://doi.org/10.1007/s12144-016-9432-4

Hackathorn, J., & Ashdown, B. K. (2021). The webs we weave: Predicting infidelity motivations and extradyadic relationship satisfaction. The Journal of Sex Research, 58(2), 1-13. https://doi.org/10.1080/00224499.2020.1746954

Hair, J. F., Anderson, R. E., Tatham, R. L., & Black, W. C. (1998). Multivariate data analysis (5th ed.). Prentice-Hall.

Hair, J. F., Black, W. C., Babin, B. J., Anderson, R. E., & Tatham, R. L. (2009). Multivariate Data Analysis (7th ed.). Prentice-Hall.

Hertlein, K. M., & Skaggs, G. (2005). Assessing the relationship between differentiation and infidelity: A structural equation model. Journal of Couple & Relationship Therapy, 4(2-3), 195-213. https://doi.org/10.1300/J398v04n02_16

Isma, M., & Turnip, S. (2019). Personality traits and martial satisfaction in predicting couples’ attitudes toward infidelity. Journal of Relationship Research, 10(13), 1-5. https://doi.org/10.1017/jrr.2019.10

Jones, D. N., Olderbak, S. G., & Figueredo, A. J. (2011). The intentions towards infidelity scale. In T. D. Fisher, C. M. Davis, W. L. Yarber & S. L. Davis (Eds.), Handbook of sexuality-related measures (3rd ed., pp. 251-253). Routledge.

Kline, R. (2011). Principles and practice of structural equation modeling (3rd ed.). Guilford Press.

Kloubučar, N., & Simonič, B. (2017). Causes of divorce from the perspective of females in Slovenia. Journal of Divorce & Remarriage, 58(4), 1-13. https://doi.org/10.1080/10502556.2017.1300024

Liu, Y., & Zheng, L. (2019). Influences of sociosexuality and commitment on online sexual activities: The mediating effect of perceptions of infidelity. Journal of Sex & Marital Therapy, 44(5), 1–11. https://doi.org/10.1080/0092623X.2018.1549632

Lisman, C. G., & Holman, A. C. (2021). Cheating under the circumstances in marital relationships: The development and examination of the Propensity towards Infidelity Scale. Social Sciences, 10, 392. https://doi.org/10.3390/socsci10100392

Look, A. E., Flory, J. D., Harvey, P. D., & Siever, L. J. (2010). Psychometric properties of a short form of the affective lability scale (ALS-18). Personality and Individual Differences, 49, 187-191. https://doi.org/10.1016/j.paid.2010.03.030

MacCallum, R. C., Browne, M. W., & Sugawara, H. M. (1996). Power analysis and determination of sample size for covariance structure modeling. Psychological Methods, 1, 130-149. https://doi.org/10.1037/1082-989X.1.2.130

Marôco, J. (2014). Análise de equações estruturais: Fundamentos teóricos, software & aplicações [Analysis of structural equations: Theoretical foundations, software & applications] (2nd ed.). CAFILESA.

McQueen, P. (2021). Sexual interactions and sexual infidelity. The Journal of Ethics, 25, 449-466. https://doi.org/10.1007/s10892-021-09359-1

Moller, N. P., & Vossler, A. (2015). Defining infidelity in research and couple counseling: A qualitative study. Journal of Sex & Marital Therapy, 41(5), 487-497. https://doi.org/10.1080/0092623X.2014.931314

Netemeyer, R. G., Bearden, W. O., & Sharma, S. (2003). Scaling procedures: Issues and applications. Sage.

Norona, J. C., Olmstead, S. B., & Welsh, D. P. (2017). Breaking up in emerging adulthood: A developmental perspective of relationship dissolution. Emerging Adulthood, 5(2), 116-127. https://doi.org/10.1177/2167696816658585

Omarzu, J., Miller, A., Schultz, C., & Timmerman, A. (2012). Motivations and emotional consequences related to engaging in extramarital relationships. International Journal of Sexual Health, 24(2), 154-262. https://doi.org/10.1080/19317611.2012.662207

Pinto, R. & Arantes, J. (2017). The relationship between sexual and emotional promiscuity and infidelity. Athens Journal of Social Sciences, 4(4), 385–398. https://doi.org/10.30958/ajss.4-4-3

Rayesh, N., & Kalantar, S. M. (2018). The role of praying for the spouse and sanctification of marriage in reducing infidelity. Mental Health, Religion & Culture, 21(1), 65-76. https://doi.org/10.1080/13674676.2018.1447555

Rodrigues, D., Lopes, D., & Pereira, M. (2016). ‘‘We agree and now everything goes my way’’: Consensual sexual nonmonogamy, extradyadic sex, and relationship satisfaction. Cyberpsychology, Behavior, and Social Networking, 19(6), 373-379. https://doi.org/10.1089/cyber.2016.0114

Rodrigues, D., Lopes, D., & Pereira, M. (2017). Sociosexuality, commitment, sexual infidelity, and perceptions of infidelity: Data from the Second Love web site. The Journal of Sex Research, 54(2), 241-253. https://doi.org/10.1080/00224499.2016.1145182

Scheeren, P., Apellániz, I., & Wagner, A. (2018). Marital infidelity: The experience of men and women. Trends in Psychology, 26(1), 355-369. https://doi.org/10.9788/TP2018.1-14Pt

Silva, A., Saraiva, M., Albuquerque, P., & Arantes, J. (2017). Relationship quality influences attitudes toward and perceptions of infidelity. Personal Relationships, 24(4), 718-728. https://doi.org/10.1111/pere.12205

Stavropoulos, V., Beard, C., Griffiths, M. D., Buleigh, T., Gomez, R., & Pontes, H. M. (2018). Measurement invariance of the Internet Gaming Disorder Scale-Short-Form (IGDS9-SF) between Australia, the USA, and the UK. International Journal of Mental Health and Addiction, 16(2), 377-392. https://doi.org/10.1007/s11469-017-9786-3

Toplu-Demirtaş, E., Akcabozan-Kayabol, N. B., Araci-Iyiaydin, A., & Fincham, F. D. (2022). Unraveling the roles of distrust, suspicion of infidelity, and jealousy in cyber dating abuse perpetration: An attachment theory perspective. Journal of Interpersonal Violence, 37(3-4), 1432-1462. https://doi.org/10.1177/0886260520927505

Træen, B., Kvalem, I., Hald, G., & Graham, C. (2022). Extradyadic activity in European older adults. Sexual and Relationship Therapy, 31(1), 125-138. https://doi.org/10.1080/14681994.2019.1685085

Warach, B., Josephs, L., & Gorman, B. (2018). Pathways to infidelity: The roles of self-serving bias and betrayal trauma. Journal of Sex & Marital Therapy, 44(5), 497-512. https://doi.org/10.1080/0092623X.2017.1416434

Wilson, K., Mattingly, B., Clark, E., Weidler, D., & Bequette, A. (2011). The gray area: Exploring attitudes toward infidelity and the development of the perceptions of dating infidelity scale. The Journal of Social Psychology, 151(1), 63-86. https://doi.org/10.1080/00224540903366750

Whisman, M. A., Gordon, K. C., & Chatav, Y. (2007). Predicting sexual infidelity in a population-based sample of married individuals. Journal of Family Psychology, 21, 320-324. https://doi.org/10.1037/0893-3200.21.2.320

World Medical Association (2013). World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA, 310(20), 2191-2194. https://doi.org/10.1001/jama.2013.281053

Wróblewska-Skrzek, J. (2021). Infidelity in relation to sex and gender: The perspective of sociobiology versus the perspective of sociology of emotions. Sexuality & Culture 25, 1885-1894. https://doi.org/10.1007/s12119-021-09845-6