>>935729174
He wants to fuck your girl, and he's gauging your reaction to see how upset you'd be when you find out.
If I were you, I'd get your name off the lease and stop being friends with this guy, because he won't stop, your girl will find his advances endearing, and eventually give in. I've seen this shit time and time again, they're called "buddy fuckers", because they buddy up to you, then fuck your girl.