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10 Key Reasons Why a Partner Might Cheat

7. "If I knew that they'd never find out ..."

Key points

  • Infidelity remains a top reason for divorce. While divorce rates have decreased over the last few decades, a large portion of couples split up.
  • Understanding the risk factors for infidelity make it possible to predict the chance of staying together.
  • Identifying areas of heightened risk may enable couples to take corrective action if they want to prevent divorce and seek satisfaction together.

It is not a lack of love but a lack of friendship that makes unhappy marriages. — Friedrich Nietzsche

We live in a time when relationships, sexuality, and identity are being reconceptualized. At the same time, infidelity and marital difficulties have been the stuff of legend and literature since the earliest recorded history. Religious texts, literature from every culture, entertainment, and everyday social discourse abound with titillating and trouble tales of betrayal and transgression. The tension between fear and fascination, moral condemnation and justification, the need for stability and novelty, and myriad other dissonances and drives make commitment and vow-breaking intensely interesting.

The Changing Landscape of Long-Term Commitment

Modern marriage is a shifting target as culture evolves faster than we can adapt, as technology connects us and alienates us from one another, and as medical and health advances extend the human lifespan, reframing what “‘til death do us part” actually means. Per the CDC, as of 2019, there were over 2 million marriages in the U.S., representing a marriage rate of 6.1 per 1000 people. The number of divorces was almost 750,000 that year, with 2.7 out of every thousand people getting divorced. Currently, about 40 percent of marriages end in divorce, down from 50 percent a few decades ago, as people work harder to stay together.

The most reported causes of divorce include lack of commitment and infidelity, followed by excessive conflict and argument, getting married too young, financial strain, alcohol and substance problems, and domestic violence (e.g., Scott et al., 2013). As reported by Lișman and Holman (2021), rates of extramarital affairs range from 30 to 60 percent for married men and 20 to 50 percent for married women, causing pain and suffering, mistrust, and uncertainty often precipitate break-up. These numbers stand in contrast to surveys showing that most people believe extramarital affairs are “morally unacceptable” (Pew Research Center, 2013), reflecting that drivers of infidelity go beyond values and beliefs.

Developing the Propensity Towards Infidelity Scale

Lisman and Holman discussed risk factors for infidelity in their work developing and validating the Propensity towards Infidelity Scale (PTIS), intended to estimate an individual’s predisposition to unfaithful behavior among those married for a significant period.

An accepted model of infidelity posits five motivational domains which drive extramarital relationships: Sexuality, lack of satisfaction; Emotional Satisfaction, being unhappy or emotionally deprived; Social context, if circumstances make infidelity more likely such as prolonged separation; Attitude-norms, for instance, if other couples are known to be having extramarital affairs; and Revenge-hostility, in retaliation after a partner cheats.

Using this five domain model, researchers conducted a two-stage process first to identify a large set of questions and see what underlying factors were associated with the tendency to go outside the relationship, and then tested this model to refine a final set of questions and correlate them for validity against existing concepts related to infidelity and commitment.

In the first step, for each of the five elements above, they generated five questions for a total of 25 items. These 25 items were presented to 330 heterosexual married participants, average age 37 (from 24 to 62 years old, about half women), who were married on average for a bit over ten years. They were asked which factors would most likely contribute to future infidelity. Their responses were analyzed statistically to determine the best fit for the data. They found that although there were several motivational categories, a single factor model best fit the data. This suggests that multiple motivations converge to predispose to infidelity. A few of the items individually overlapped, leading to a final set of 21 items after the first stage.

In the second step, researchers took the 21 items from the first study. They compared them against several accepted scales measuring infidelity and morality with 288 participants of similar age, gender, and marital lengths as the first study. They completed the 21 items draft of the Propensity toward Infidelity Scale under development, the Intentions toward Infidelity Scale, the Infidelity Scale, the Moral Identity Questionnaire, the Morality Founded on Divine Authority Scale, and the Utilitarianism Scale.

Further refining the initial 21 items in the PTIS, they removed items one by one, which did not contribute to infidelity tendency to arrive at a final model which best fit the data. This model had ten items in total.

Ten Risk Factors for Infidelity

This final ten-item PTIS correlated well with other infidelity measures, and reverse correlated with morality measures (i.e., greater sense of moral self, a greater sense of moral integrity was associated with lower tendency to cheat), as would be expected for a valid set of questions estimating future unfaithfulness. Each of the ten items was distinct from one another and contributed significantly. Stronger agreement with each of these items contributed to a greater predicted tendency to engage in extramarital relationships:

1. If my spouse were unfaithful, it would seem natural to me to have an extramarital relationship.

2. Flirting with another person would make me feel wanted.

3. The lack of sexual relations with my spouse would be a reason for me to have an extramarital relationship.

4. It is plausible for me to have a relationship with someone else than my spouse if I feel emotionally bonded to him/her.

5. My spouse’s long-term absence would make me engage in relationships with other people.

6. Colleagues of the opposite sex represent a potential opportunity for an extramarital affair.

7. If I knew that my spouse would never find out, I could have an extramarital affair.

8. There are certain contexts in which it would be plausible to have an extramarital affair.

9. My spouse’s close relationship with a colleague of the opposite sex would make it likely for me to engage in a relationship with someone else.

10. The fact that other married friends have had extramarital relationships makes me think that it can happen to me.

Applying the PTIS

Future research needs to be conducted to see if the PTIS predicts infidelity in marriages and other relationships. The way to test this would be to have people complete the scale early in or before marriage and then follow up with them years later to see if people who scored high on the PTIS went outside of the relationship. Future research could test predictive power and couples applications1.

Addressing areas of concern, such as low sexual satisfaction or emotional distance, and managing the context to reduce the risk, for example, avoiding prolonged separation or exposure to tempting others, or addressing feelings about other couples’ infidelity (and perhaps a history of parental infidelity), would be expected to reduce the risk of infidelity and protect the marriage. Couples may also focus on known factors desirable in long-term relationship partners to leverage reducing risk with increasing protective factors.

Suppose there is a shared motivation to stay together and seek fulfillment. In that case, couples can use knowledge of infidelity risk and tools for assessing risk to secure a better chance of having a satisfying long-term relationship.

Facebook image: antoniodiaz/Shutterstock


1. It could be tested cross-sectionally by having people complete the PTIS and seeing how many of them had past infidelity. For now, this research shows that the 10 items PTIS is valid internally, that is each item gets at a unique factor, and that it correlates with other accepted infidelity and morality measures.

Because it is a self-report scale, it relies on honest and accurate reporting to be reliable. The items themselves are useful for individuals to privately inventory their own propensity toward infidelity, and for couples and couples therapists to look candidly at their risk for infidelity and identify potential targets for intervention.

Scott, S. B., Rhoades, G. K., Stanley, S. M., Allen, E. S., & Markman, H. J. (2013). Reasons for divorce and recollections of premarital intervention: Implications for improving relationship education. Couple and Family Psychology: Research and Practice, 2(2), 131–145.

Lișman CG, Holman AC. Cheating under the Circumstances in Marital Relationships: The Development and Examination of the Propensity towards Infidelity Scale. Social Sciences. 2021; 10(10):392.

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