It's horrible to say but I usually wait until I can't stand the person... it's really not good for me or him but I feel too bad breaking up ahead of time when he first starts to bother me... I've had three boyfriends. The first broke up with me (I later found out he was a huge liar so that was for the best), and the other two I really don't even like to talk to anymore because they bother me so much... Isn't that aweful?!
Anyway, to answer your question, I guess you'll just /know/. I think you should be able to tell just by looking at them. Just don't follow my examples and wait too long to break it off!
