I know it's hard on men. I know that. But hateful harpies don't just end up in the lives of innocent men who don't invite them there. And I know from watching friends, that bad marriages are almost always bad for both sides. Women don't enter marriage just to screw men for money. People enter marriage, some are good at getting along, some are good at being married, and some are not. Some men marry women that have a 'bitch' sign flashing over their heads that was always there but they didn't notice till the sex stopped. Divorce is high because people are spoiled. Men and women.
I feel little to no sympathy for people who claim their spouse suddenly became the devil overnight. There's always two in any tango. The nastier it is, the more both sides had to act to make it that way. That's just the way it is.
I think you're mistaken. Some people really do change, or they hide who they are for a long time. My brother knows an older couple who were married for 41 years, had grown kids, etc. Seemed like normal church-going midwestern folks. One day, the husband announces he's leaving for some young *guy* he met on the internet. Should she have seen that coming, back in the early 1960s?