Why do guys annoy girls when they like them?

A guy in my band class is always trying to annoy me, and talk to me. When he is talking to me he seems like he really likes me, but he found out that I like him, and now he is avoiding me. I don't know what to do about that, but what I am really wondering is why I like him, and why he keeps annoying me(if he does like me.) I asked my friend why she thinks that I like him, and she thinks that it is because he annoys me, and I don't really understand this, so if you could help then that would be great.
Why do guys annoy girls when they like them?
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