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

Sexual behavior is motivated by more than just pleasure or reproduction. “Duty Sex” refers to sexual activity motivated by obligation and a desire to maintain one's romantic relationship. From an evolutionary perspective, such behavior can be understood as a mate retention tactic, functioning to preserve romantic relationships when they are threatened. We therefore tested whether perceived probability of partner infidelity, mate value discrepancy, and neuroticism predicted Duty Sex engagement in 252 participants. Duty Sex frequency did not differ by sex. In pooled analyses, higher perceived probability of partner infidelity, lower mate value relative to one's partner, higher neuroticism, and being in a committed rather than casual relationship were associated with greater Duty Sex engagement, but relationship length was not. In sex-stratified analyses, perceived probability of partner infidelity and neuroticism were associated with greater Duty Sex in both women and men, whereas lower relative mate value was associated with greater Duty Sex in women only. However, tests comparing the strength of each association between women and men found no significant sex differences. Our findings are consistent with evolutionary models of mate retention, and provide insight into how cues of relationship threat may motivate sexual behavior.