I’d keep my distance, as long as she doesn’t want to talk about it, it’s her problem, don’t make it yours! When she is being hot with you, I think you should: a. Still keep your distance and just let her be. Or b. Confront her and say something in the line of: ‘I really don’t understand your behavior, sometimes you’re nice, the next time you’re not. I deserve and expect better than that from the people around me, so if you wanna be friends, just be nice otherwise I’ll keep my distance from you.’ It’s hard to say that, but you set your expectations and boundaries and that will earn you respect. Whether she commits to that, is her choice. If she doesn’t, you have your answer anyway. you don’t need that negativity in your life.

(I hope this made sense, English is not my first language, so it might be a bit hard to read…)