Is it an abusive relationship if your boyfriend moves out on you 5 times in 2 years with no good reason?
I don't know about abusive but you need to get rid of him. Don't
let him keep leaving and coming back. He obviously has a reason or
he wouldn't leave, maybe he just isn't telling you. You deserve
better than that. He's probably not worried because he knows that
if he leaves you'll let him come back. Next time he says that he is
leaving you need to explain that if he leaves again, instead of
staying to talk over what the problem is, then he is not coming
back!! If you stay with this person, you are an idiot.