I`ll try make this short and just include what I think is important.

There`s this chick I`ve been going out with since march, in August she decided to just ignore me on bbm, and her number changed. The following month she had a rebound fling that lasted less than a month but during that period she started inboxing me on fb and gave me her bbm pin. we started chatting again and she was flirty with me. The week later i pulled out and I found out she broke up with the old dude but now she`s with some other dude. Even made this one a pro pic, She hasn`t slept with him though so I want to know, how can I get her back cause I really love her. Heck I stumbled on the PUA society trying to find ways to get her back. Does anyone have an idea on where to start?

Move on, cut off contact and game other girls, become a better person, a more attractive man with an abundance mentality and outcome independence and then maybe.... Maybe she will come back to you.