Unfortunately for women, as time goes on they become less attractive, and the guys that used to be interested in them are now only interested in younger, prettier girls. While men tend to become more physically attractive and develop in their careers as they age, the exact opposite happens for women. Because of all this, men try to become alpha males and don't treat women well if they are, because they don't need to.
In my own experience, this is all essentially true. A friend of mine was recently given an ultimatum, by one of the several women he's been sleeping with. He could care less, she's easily replaceable. And he doesn't care because attractive women wouldn't pay attention to him a few years ago. Looks like women created a cycle that men are abusing.