Whats her Game? why does she do what shes doing?

so theres this girl ive known since she was 14. im 22 shes 18 now. i always had a thing for her. mainly because how she was raised is near identical to me she has been in 42 foster homes. ive been in 39. its rare i meet others who truly understand what thats like. in any case. over the course of 4 years we talked on and off. but she mostly sent me off during that time. i only got the chance to hang with her 4 times in the 4 years. i finally sent her a message saying im going to stop talking to her and forget about her for good... well once i did that she all of sudden was willing to hang out in person again. she even went as far to move into my apartment for few days... we had sex a few times and everything was good until one day she just started pushing me away again. didn't wanna kiss me nothing. i know when a girl is avoiding getting close to people out of fear... this isn't that because its different shes far from shy. shes VERY popular with the guys if you know what i mean but she sends off most of them she lets them all think shes going to let them have sex with her.. but she never does im like the 3rd guy shes slept with i know because ive been in her facebook before. thats how i know im different from the rest she put on this "hood" act when i know thats not really her ive known her since she was 14. this act she puts on started only 2 years ago. shes originally from a very small town up northern MN only white people in any case she moved out 2 days after she moved in