People sleep together, somehow, and continue that path to its eventual destruction.
Thats all.
So is the solution not sleeping together?
Depends on the people.
Some people die before they reach the conclusion. Some people break up before they die. But if people lived infinite lives, they'd all break up. Which leads me to the conclusion that no relationship should ever be expected to be forever. People change, and it can't be assumed that people will be willing to continue on with you, as you and they become different people over the course of your evolution.
I say, smoke em while you got 'em. If you're getting along, fine. If you're not... and you're young... don't put up with an exorbitant amount of bullshit.
When people get older, you allow for a certain amount of qwerks and idiosyncrasies. No outright throwes of physical hostility, I think is the approved line.