Guy sucks his teeth when he sees me?

Why would a guy get like an attitude when he sees me?

He had a crush on me he took something I did as rejection and then I went out of my way to make conversation and talk to him to make up for it but he always kind of ran away from me. Now he avoids me. When he walks by me and notices me he gets an attitude. I don't understand why.
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I looked up "sucking teeth at someone" as body language and it means that they have contempt for the person? Why would he have contempt for me? I've been nothing but nice to him.
Guy sucks his teeth when he sees me?
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