I'm curious, why do men lead women on?

You could be falling for him, but obviously he is not ready yet. Do not be serious. Do not call/text him. Let him text/call you first. Do not be too easy to get for him. Guys fall out of interest if a girl is too easy and not challenging anymore. I am not saying you are easy, but make yourself less or unavailable to him. And he'd sure be chasing you!