Why does he smile when he sees me if he’s not into me?

This guy that I like and he likes me too. I think he only likes me cause I like him. He is always happy to see me but doesn’t really talk to me. He avoids me but he smiles when he sees me. I asked to hang out with him many times but he says things like he’s busy or he gives me negative body language (like turning his back to me). He acts like he’s into me so I know it’s more than friendly but he doesn’t want to take me on a date. He tells me I’m beautiful and shows me off to his friends but that’s all.
Why does he smile when he sees me if he’s not into me?
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