Guy's Behavior

Why does he stare at me while talking to/dancing with another girl?

I'm kind of into this guy and he's told mutual friends he thinks I'm cute as well. They told me he was telling all "the boys" that he thinks I'm cute. We did text for a bit and he asked me if I was going to this club and I said yes.

While we were there at the club on the night out, this girl we both know came onto him and started dancing on him, so I walked over to my friends and started talking with them. But I looked across the room and I saw him with the other girl basically attached to him but he had turned to face me and was staring at me not really interacting with her and stood there watching me talk to my guy friend from across the room.

He tends to do this quite a lot. When he's talking to other people if I walk by he will just watch me and I see it out of the corner of my eye. But we don't actually talk much. Is he just shy or uninterested? Why dance and talk with another girl then.
Why does he stare at me while talking to/dancing with another girl?
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