Some women treat men with contempt in an attempt to get the men to do more for them, in order to “earn” women’s approval. A woman who gives lots of admiration undercuts that scheme, and gets resented. It’s worse if she’s younger and more beautiful than the contemptuous wives, as it causes the husbands to think “Why do I stay with my wife when there are women like this one out there?”
Which is a damn good question. With the emphasis more on the contempt and disdain than on the youth and beauty.
I wonder how many of the women who complain about being dumped for a young hotty treated their husbands this way when they had him. But of course his leaving could not possibly have anything to do with anything she did.
Which is not to say that many men aren't indeed pigs.