Please answer my question !?

Be very sure of your feelings before you make a move. You may be giving up a BF who is there for you, for a guy who is making a move on a girl who is involved with in a relationship. It's not very kosher....Don't be led astray by this guy.....he doesn't sound like a good risk...Take it slow...sooner or later, you'll know what he's up to.....good luck.