What should you do when a guy breaks up with his gf then tell his bff he likes you and then gets back together with his ex girl friend because he says he doesnt know how to end since its been soo long?

Then that's just messed up... you can ask the bff "then why is he dating that girl if he likes me?" or you can just approach him directly and say .. "look, either you like me and you're dating me or you're in love with that girl. Period." He can't have it both ways.