Sexual jealousy in humans

Sexual jealousy is a special form of jealousy in sexual relationships, present in animals that reproduce through internal fertilization, and is based on suspected or imminent sexual infidelity. It is founded on the instinct of keeping genes in the gene pool and expecting sexual partners to care for the offspring. The concept is studied in human and non-human primates in the field of evolutionary psychology.

Evolutionary psychologists have suggested that there is a gender difference in sexual jealousy driven by men and women's different reproductive biology. For men it is felt as a threat to his relationship's future because he could be cuckolded into raising children that are not his own. For women they can lose their relationship and all the benefits that entails to another. Research has shown that men are impacted more by sexual infidelity, while women are more impacted by emotional infidelity.

An alternative explanation is from a social-cognitive perspective. Typically men will place a lot of importance on their masculinity and sexual dominance. When the male's partner commits infidelity, these two components of his ego become severely threatened which is why men are more upset when a partner has sex with someone else. In contrast, women invest a lot of emotion into a relationship and will experience a threat to their self-perception when a partner commits infidelity, hence why women are more concerned with emotional infidelity rather than the sexual kind.

Some research has suggested that there are no sex differences in sexual jealousy, concluding that males and females both equally experience distress over emotional and sexual infidelity. Sexual jealousy is cross-culturally universal but how it manifests itself may differ across cultures.

Psychologists have found that males react very strongly to sexual infidelity, whereas females are more likely to forgive a one-time sexual adventure if it does not threaten the male parental investment. Therefore, jealousy is likely to be evoked in females if they feel that their partner may leave them for another woman; this has been shown to be more likely to occur if the male commits emotional infidelity. Emotional infidelity occurs when one partner develops a meaningful, emotional attachment with someone outside of their primary romantic relationship.

...
Wikipedia