Horrible human beings get together for a reason, you know.

A person who has serious flaws like, let's say, being vicious and stupid, is always going to feel stifled and resentful if they pair up with a person who is decent or intelligent, or just objects to stupidity or viciousness. If such a person finds another person who's also vicious and stupid, and they can both feel free to be themselves within the relationship, in a way they could never be with a nice or vulnerable person. Such relationships can feel liberating and passionate, at least until they turn on each other and start to tear each other to shreds, which they always do.

I think this explains a lot about a certain celebrity relationship that's still in the news, FOUR YEARS after the divorce.