WHY!!! come everytime I break up with my ex....?

She always try to come back soon as I'm trying to get over her? We've broken up twice now TOTAL. This will be our third time, but we haven't seen each other in a while since she has been attending college (and all we did was bicker with each other). But since we've seen each other its calm down a lot the arguing that is. But I don't know I always question US because she gets these ridiculous attitudes and she tells me how guys are trying to talk to her. How can I be sure that this will work, so I wont be wasting our time again?