Why do u think she avoided me & gets so nervous?

[Chris]

As someone who is being trained in social psychology, I have a few theories.

1) It's almost exactly as you say: that first night where you two did a lot of stuff together may have felt good at the time, but later she might have regretted it, even moreso if she initiated most of it as you described. That being the case, the sight of you would invoke unwanted memories, perhaps because she is afraid of the thought of being a lesbian. It is very common around people who have yet to come out of the closet.

2) A bit of a stretch, but not out of the question. She could have a mild form of multiple-personality disorder, in which one side of her truly enjoyed what happened that night while her other half firmly resented it.

3) She may feel like she acted too boldly, and took things out of her comfort zone because it felt right at the time. This oftentimes leads to an inner struggle about what is right and wrong. Her attempts to remain warm/flirty at times may be because she's trying to establish some normality.

Those are what I can think of at the moment.