Can chemistry be over just like that?

I met this guy last august. I inmediately like him (I don't usually do) and I went to his place w/friends to have dinner. That was the third time we see each other. The chemestry was so strong you almost could see it in the air. we flirted a lot. The next time I saw him, like nothing at all. Next time, he couldn't stop looking at me. but he haven't done any moves, even when I have cue him (in several ways) I am interested. What is that? Can chemistry be over that fast? Why he doesn't even try? Why do you guys just kinda dissapear after you tell her you want to make love to her? Don't get it.