Thoughts on male and female jealousy

After a conversation I had with someone the other evening, we came up with the following hypothesis. Jealousy is different in males and females, and seems to follow opposite (and hence equally irrational) order considerations. Men seem to be more jealous when their partner (either monogamous, polyamorous, or whatever) is seeing or in love with somebody that they consider inferior, a jerk, 'don't know what she sees in him.' On the other hand, women are more jealous when their partner (or former partner) is with a younger, more attractive, or accomplished woman, whereas they are less sensitive to him seeing a woman they consider inferior. For either sex, their view of the ordering seems the only rational one but clearly neither way is rational.

I wonder what you think of this hypothesis. Please feel free to add examples and counter-examples in your comments. In particular, I would be interested in finding out whether a man would feel more jealous if his former partner were with a jerk. It makes no sense to me that he would, but then the whole male perspective on jealousy makes no sense to me, and seems to hark back to primate ancestors giving in to the alpha male, never mind droit de seigneur. And how does it work for gays, lesbians, and others?