Don’t keep your enemies close
Do not, under any circumstances, befriend the guy’s girlfriend! You may do this and hardly understand, in the midst of all your confusing emotions, why you are doing it. You may do it because it lets you be closer to him. But it is absolutely the cruelest thing one woman could do to another—gain her trust, to betray it in the biggest way. She isn’t your friend now and she doesn’t need to be.