Evolutionary theory based research shows that women and men can differ in their responses to sexual and emotional infidelity. However, research has not examined the question of whether men and women react similarly or differently to a partner's engagement in different types of sexual infidelity. The present research sought to answer this question. Based on the aforementioned prior research, and short term mating desires, sex differences in reactions to different types of sexual infidelity were

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... ot expected. Both women and men were expected to report higher levels of upset when a partner engaged in sexual intercourse rather than when a partner engaged in oral sex, heavy petting, or kissing with another person. The results were consistent with the hypothesis. Both men and women were most upset by a partner's engagement in sexual intercourse with another person. These findings are discussed in terms of prior research.