<human>: Can you summarize the given text in a few sentences?

My best friend who does not use Reddit asked me to post this for him since he knows I'm on Reddit but here it is.

My friend is 19 years old and his girlfriend is the same age. They have been dating for almost 3 years now (off and on dating the past 2). Pretty much the case is that he can't stop going back to her. She is very manipulative and has even attacked my relationship AND my girlfriend on a personal level basically saying I'm a "bitch" because my girlfriend and I don't fight and my girlfriend is a slut and a hoe. 

Reddit what are some tips for my buddy to get over his girlfriend and finally end it. They have been like this for about a year now and it's gotten pretty bad. He now currently moved to FL and she lives in IA (same state as us) and he is coming back after the summer and I don't want him to be with her. She makes him miserable and he wants out desperately but he says he can't because that relationship is all he knows. Thanks!
<bot>: My friend wants out of his relationship of 3 years but says he doesn't know how because it's all he knows.