I hardly know him, so why can't I stop thinking about him?

So I've just gotten a new job and one of the guys that already works there seems pretty cute. I've spoken to him a few times, but I hardly know him, but then I find myself going home and all I can think about is him, I feel stupid, because like I said, I barely know this guy, so what the hell is going on?
I hardly know him, so why can't I stop thinking about him?
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