Why so rude? Guys?

I had a crush on a guy since school. He knew it. So he always look at me smile when I am laughing with my friends. Stare. Wink at me. Be very kind. But when I just didn't smile back when he was smiling. He started acting rude. He started making me jealous. He would sometimes talk bad about me in front of me. Try to hurt me in many ways. Whenever I text him reply to me coldly. I would always ignore him. He would always try to get my attention. Why is he acting like this. I still like him he knows it but now he just doesn't care about how I feel. I know I have to move on , still.
Why so rude? Guys?
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