What would you think it means if a girl does this?

So I know this girl in my major at school who has a bf. Me and her had an interesting short history while at school. Anyway she has a bf( I personally do not understand why she is with this guy at all..it puzzles me to say the least). Anyway more then a month ago I texted her and we talked a little past 11. Before that I had gotten weird signs from her that she likes me, etc leave her bf. A week and a half later I asked her how her and her boy were doing? (I honestly thought I had every right to that question. Guess what she does? Not text me back). Why? I made my interest clear in the beginning, but then found out she had a bf. So I backed the **** off. Then she made it seem like she didn't want anything to do with me. So then she started acting differently when she saw me with another girl so that is what led to the above. This girl that I am talking about ruins conversations with other girls and is plain noisy sometimes. I mean the next day she was happy for me and a couple other students to use her for something that she had already done. Then when I found out she had a bf. all she said was pretty much (cuz she mentioned date). Then asked her who he is was? No response either. I can't see her right now. Way early on in the semester I was sitting with her best friend(I didn't know this girl had bf, but I just saw her as this attractive girl that I liked as a friend). She comes up and says how did you two meet? Clearly, she was a little jealous I was talking to her friend.