Men have never been good at monogamy in the history of relationships. The only difference now is that women are trending that direction too. Feminism didn't kill monogamy, only exposing that it had never been alive.
The range of her options really has expanded. We've finally reached a point in history where a woman can earn enough to support herself, and single motherhood no longer makes her a pariah. If a man doesn't treat her right, she can move on because she's no longer financially bound to him. If she can't find one she likes - or one who likes her - she can keep looking.
Basically, women are negating the advantages men have always held, and men are furious.
And that's what I meant by hypocrisy.