What are the reasons a guy would try to physically avoid you for?

I have a guy that I’ve been wanting to talk to on a campus for a very long time. However, he hasn’t been coming to class very often anymore and resorts to hiding in another room/place before we have to chance to be near together. Whenever we happen to be together, he runs off to the bathroom mid-way through the class. He’s been giving mixed signals and I hear from some people that he doesn’t want to talk, but I don’t even know what I did to upset him. Please , help me out in understanding his boundaries.
What are the reasons a guy would try to physically avoid you for?
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