it sounds like this guy does have a thing for you and he wont be the last. But here is my advice: Never date someone who leaves someone else to be with you for he will leave you to be with someone else.
If you want to have a fling with him, this is your chance, but don't do anything you would regret because most guys that age are only after one thing and once they get it, they are gone. Look how he talks about his girlfriend, that could be how he'll talk about you.
Good luck on figuring things out.