I am in a relationship that I feel trapped in. He is a great guy but...

Well, like me, I get extremely jealous. He just really doesn't want you to get anywhere close to falling for another guy. Talk to him and promise him you won't ever cheat on him, or if you would... then break up with him.

I would talk to him about it. Tell him how you're feeling and see what he says. You shouldn't feel trapped if you love someone... and it sounds as though he may have some trust issues. It's better to end it now then to wait until his feelings are REALLY in it... It will probably hurt him either way, but if you can't talk it out, I'd walk away now for his sake.