Why would a guy say “it is a mess” when he has started dating this woman in the past month but he flirts with me?

He teases me, stares at me when I’m not looking, watches me talking to other men, and the other night when we were drinking he took my hand and began stroking it tenderly with his thumb ie the thumb thing. He likes this other girl but he may like me too but I’m not sure.
Why would a guy say “it is a mess” when he has started dating this woman in the past month but he flirts with me?
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