Men become very upset, even violent, at an instance of sexual indiscretion by a mate. Women, on the other hand, have bodies that run on a proportionately small amount of food in comparison to males. They use this energy efficiency for gestation and lactation. Their relatively high paternal investment is to pass their genes on. In the human species, because of low male sexual dimorphism they require a higher level of investment from men.
Women raise their children and expect and require resources from their mates.
In summary high male investment explains the relatively weak sexual dimorphism in humans, while the necessity of paternity confidence has led to human males having sexual jealousy marked by violence and consistent attempts to restrict the sexual behavior of women. Female jealousy is centered more on concerns related to paternal investment than on male extrarelationship sexuality per se, as greater paternal investment should increase the chance of survival for the female's offspring. In short, sociobiological theory holds that female jealousy is marked by fear and anxiety over losing the relationship and by an interest in the nature of the rival relationship, whereas male jealousy, focusing on the sexual threat of the rival, is marked by competitiveness and aggression, and is much less affected by situational factors suggesting that the mate is still interested in maintaining the primary bond. It is not just Christianity, in which Jealousy plays a role. Stories abound in mythology of Jealousy and the havoc it wreaks.