Who Engages in Duty Sex?—Infidelity Concerns and Mate Value Discrepancies

• Duty Sex: Sex motivated by a sense of obligation, such as avoiding a partner’s anger, loss of love, or leaving, rather than by desire.

• Mate retention: Behaviors that help someone keep their current partner.

• Benefit-provisioning tactic: A way of keeping a partner by increasing their satisfaction, such as giving gifts, showing love, or offering sex. It is distinct from tactics that inflict costs, such as insulting or threatening a partner.

• Mate value: How desirable a person is seen to be as a romantic or sexual partner.

• Mate value discrepancy: One’s own perceived mate value minus one’s partner’s. A negative number means you see yourself as “lower” than your partner.

• Perceived probability of partner infidelity: How likely you think your partner is to be unfaithful, rated 0–100%.

• Neuroticism: A personality trait marked by a tendency toward worry, anxiety, and emotional instability.

• Sex-stratified vs. pooled analysis: Analyzing women and men separately versus analyzing everyone together.

• Generalized additive model (GAM): A statistical method that can capture curved, non-straight-line relationships between variables.

• Cross-sectional design: A study that measures everything at one point in time, so it cannot show what causes what.

• Sexual compliance: Unwanted but consensual sex. It is broader than Duty Sex, which is defined by the specific motive of obligation.

The authors treated Duty Sex as a possible mate retention tactic, a behavior that may have evolved to protect relationships under threat. They tested three predictions:

1. Do people who perceive a higher chance that their partner will be unfaithful report more Duty Sex?

2. Do people who see themselves as lower in mate value than their partner report more Duty Sex?

3. Do people higher in neuroticism report more Duty Sex?

They also examined these questions in men as well as women, since earlier Duty Sex research focused mostly on women. In addition, they explored whether relationship type (committed vs. casual) and relationship length were linked to Duty Sex.

Sample and method: 252 sexually active U.S. university students (176 women, 76 men), aged 18–24, who were currently dating. Participants completed self-report questionnaires covering Duty Sex, perceived partner infidelity risk, mate value, and neuroticism. Duty Sex was measured with four items (scored 4–20) about having sex to avoid a partner’s anger or loss of love.

Overall levels were low. Mean scores were 5.24 for women and 4.76 for men, barely above the minimum of 4. Most participants reported rarely having sex for these reasons. There was no significant difference between women and men (p = .538).

Pooled analysis (all participants together):

• Higher perceived probability of partner infidelity was associated with more Duty Sex (p < .001).

• Seeing oneself as lower in mate value than one’s partner was associated with more Duty Sex (p = .002).

• Higher neuroticism was associated with more Duty Sex (p = .003).

• Being in a committed rather than casual relationship was associated with more Duty Sex (p = .013).

• Relationship length was not associated with Duty Sex (p = .125).

Women and men analyzed separately:

• Perceived infidelity probability was significant in women (p < .001) and men (p = .048).

• Neuroticism was significant in women (p = .044) and men (p = .004).

• Mate value discrepancy was significant in women only (p = .002 for women; p = .291 for men). In women, Duty Sex rose mainly at the more extreme negative discrepancies, where they saw themselves as substantially lower in mate value than their partner.

• Relationship length was not significant in either sex.

• In committed vs. casual relationships, men in committed relationships had more Duty Sex (p = .021), while the difference among women did not reach significance (p = .072).

No significant sex differences. Direct statistical comparisons found no significant difference between women and men in any of the associations: infidelity (p = .251), mate value (p = .756), neuroticism (p = .195), relationship length (p = .076), or committed-vs-casual status (p = .383). The mate value result in women alone should therefore be read as a description of the female subsample, not as proof of a sex-specific effect.

Model fit: The model explained about 40.9% of the deviance and 29.3% of the variance (adjusted R² = .293). The neuroticism effect was modest, rising only slightly across the trait’s range.

Interpretation. The authors say the results support the view that Duty Sex works, at least partly, as a benefit-provisioning mate retention tactic. They offer these explanations:

• Infidelity concerns: People may fear that refusing sex will upset a partner and raise infidelity risk. Having sex may also strengthen the pair bond. Duty Sex may be passive (complying to avoid conflict) or active (initiating strategically to keep the relationship stable).

• Mate value: People who feel “lower value” may fear losing a partner who could find better alternatives. The finding extends recent work showing that lower relative mate value predicts sexual efforts to please a partner, by showing it also relates to obligation-driven sex. The lack of sex differences suggests the pattern may not be specific to women, but larger samples are needed.

• Neuroticism: Greater sensitivity to rejection and relationship loss may drive this link. It held even after accounting for infidelity concerns and mate value, so neuroticism seems to contribute additional variation. The authors link it to attachment anxiety, which predicts sexual compliance, and to earlier findings on Duty Sex, which differ somewhat from the present sex-stratified results (possibly because the earlier measure also included coercion).

• Committed relationships: Greater investment may raise the cost of losing a partner and strengthen the motivation to preserve the relationship. Because relationship length was not a factor, the effect is not simply due to longer relationships.

Cautions the authors raise:

• Duty Sex was infrequent in this sample, so the findings should not be taken to mean it is common in most relationships. They apply to people who do engage in it.

• The design is cross-sectional and self-report, so causation and time order cannot be established.

• The sample was small and made up mostly of young university students in short relationships, which limits generalizability to older adults and long-term relationships such as marriage.

• There were fewer men than women and fewer casual than committed relationships. Power was lower for men, so non-significant male results and sex comparisons should be interpreted cautiously.

• Participants had to be currently dating and sexually active, so some selection bias is possible.

• The neuroticism measure had modest reliability (α = .60), and relationship abuse was not assessed.

Recommendations for future research:

• Use longitudinal designs to test whether neuroticism leads to greater perceived relationship threat and then to more Duty Sex.

• Study long-term outcomes: whether Duty Sex builds closeness or breeds resentment, how partners feel afterward, and whether it predicts relationship breakup.

• Distinguish passive from active Duty Sex, which may explain earlier links to sexual dissatisfaction.

• Examine relationship dynamics such as emotional or physical abuse, which could lower a person’s perceived mate value and raise Duty Sex.

• Test whether the predictors interact, for example whether infidelity concerns strengthen the mate value effect or neuroticism amplifies reactions to threat.

• Use larger, preregistered, more balanced, and more diverse samples.

Conclusion. The authors conclude that Duty Sex is consistent with an evolutionary mate retention strategy, but whether it actually stabilizes relationships remains unknown.

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