“Recent research on jealousy has been predominantly inspired by an evolutionary psychological analysis of sex-specific differences in the responses to a mate’s sexual and emotional infidelity. According to this analysis, a woman’s sexual infidelity could reduce a man’s reproductive success because of the ensuing risk of inadvertently losing an opportunity to reproduce and of investing limited paternal resources for the benefit of genetically unrelated offspring. A woman’s reproductive success, in contrast, is endangered if she loses a male’s resources and assistance in raising her offspring. A man’s mere sexual infidelity does not necessarily imply the risk of losing his paternal investment. Rather, this resource threat arises if he develops a deep emotional attachment to another mate. As a consequence of these sex-specific reproductive threats, the male jealousy mechanism (JM) is hypothesized to be particularly concerned with a mate’s sexual infidelity, whereas the female JM is hypothesized to be particularly concerned with a mate’s emotional infidelity.”
The issue is looked at in greater depth in this experimental study reported in Evolutionary Psychology.
Incidentally, the best literary treatment of male jealousy I have read yet is in “The Kreutzer Sonata” by Leo Tolstoy, which you can read here.