Unfortunately, as part of my psychology major, I've recently had to deal with the tripe/pseudoscience that is evolutionary psychology. I'm sure everyone is familiar with the naturalizing-female-subjugation-and-male-s
Apparently, in heterosexual relationships, men and women experience different kinds of jealousy over their partner's infidelity. Men are more likely to have sexual jealousy (their jealousy will be triggered by cues to their partner's sexual infidelity), while women are more likely to experience emotional jealousy (their jealousy will center on emotional infidelity/cues that signal the long-term diversion of commitment and resources, such as their mate falling in love with another woman). Apparently, this is why when a man suspects that his female partner is cheating on him, he will go into a jealous rage (e.g. punching the other man).
I was thinking about this and relating it to my own experiences. I'm a bisexual female and have experiences with men and women (albeit very limited experience with women, so maybe I don't know what I'm talking about). With my last boyfriend, I did experience more emotional jealousy than sexual jealousy when I was with him. When I sort of dated this girl back in high school, I definitely experienced more sexual jealousy than emotional jealousy. I experience sexual and emotional jealousy with both people, but I think the sexual jealousy was a lot more pronounced with the girl.
But anyway, here's my take on this (because evo psych is crap): I think jealousy has less to do with the sex of the jealous person than it has to do with the gender of the (possibly cheating) partner. I think because of my internalized conceptions of men and women, I had different experiences of jealousy with these people. I'm obviously not a sexist or misogynist, but everybody has internalized conceptions of how they believe men and women are and should be like. There's a double standard concerning sex: its considered normal for men to sleep around, but not for women. If a woman sleeps around, she is a "slut", "whore", etc. Thus, her partner's jealousy will center more on sexual infidelity than emotional infidelity.
I also think men become more sexually jealous because they have an internalized sense of sexual entitlement to women (as well as other senses of entitlement), and if somebody threatens this entitlement, jealousy will ensue.