u r young and u have low self esteem. eventually u will lose tolerance for her behavior. being alone and happy is alot better then being with her and trying to get what u need and want and cant. see her for what she is not how u want her to be. there r plenty of good people out there go find them. coming back to u when she breaks up with someone is not anything id want. she is trying out 'the next best thing' and knows she can do it. she incurs no consequences if it doesnt work out, she just returns to u. that will get old down the road. im not saying she is a bad person she just isnt that into u and u deserve better.