I don't hate Keira Knightly. I thought she was gorgeous when she first popped on the scene. But I did start finding her annoying when she opened her yap too much. Celebs just don't think before they go babbling, that's their biggest problem. Plus, let them get a little whiff of A-list and they get scarily thin and/or PS'd to the point where you wonder what made them famous in the first place.
So Jealousy? No. Flapping the jaws too much and sounding like an idiot or bitch (or both) every time they get a chance + neurotically fucking with their previously adorable looks too much = me anywhere from merely annoyed and exasperated-completely over and done with them.