I Lost a Friendship

We are from the same city and happened to move to the same new city to study. I know she probably wanted to start over and that made her reject our old town and our old friend group a little bit. I feel like that, even though at times she does seem to want me as a friend, I am part of the past. She didn't want to have a birthday party back there anymore, but I also wasn't invited to her party over here. I don't understand. She still often treats me like a friend, but I also feel like she would not have kept in touch with me had we not moved to the same city. She just can't ignore me because I am here, or something. I am her friend, but I have to stay in her past and may not intervene with her present.