Recent research has revealed that even though both men and women commonly experience jealousy, they differ with regard to its causes. For the most part, men are more likely to be jealous of sexual infidelity. The thought of their partner fooling around with another man is more than they can stand. Women, on the other hand, are more likely to be jealous of episodes of emotional infidelity - the development of a close emotional bond with another person.
There are a few theories regarding why the sexes may differ in this way. The primary theory is based on evolutionary psychology. From this perspective, men and women's feelings are based on their self-interest. Each wants to ensure the future survival of their offspring. Men view their woman's sexual flirtations with great suspicion, for fear that he'll be wasting his time raising someone else's child. Women view their man's emotional involvement as a threat, for fear of losing the best source of her child's protection.
Sugar and spice! You get equally worked up by the threat of emotional and sexual infidelity. The thought of your partner acting out scenes from the Kama Sutra distresses you just as much as your partner sharing a deep conversation with another person. We've explained why the majority of men and women tend to be more jealous of one type of infidelity, but many people (men and women alike) tend to be equally jealous of both. This pattern may stem from cultural messages we receive about the importance of sexual prowess to our self-image, and from the differing degrees of need we feel to form close bonds. In essence, it's just as important to you that your partner be your best friend as well as your lover.