Bad boyfriend of my girlfriend! What is he doing to me?

I was visiting my girlfriend Lisa today, but suddenly her boyfriend was standing behind me and groping me, it was quite embarrassing for me.... At any moment his girlfriend could come in.... Apparently he fancies me... I dont think its a good idea to make out with my girlfriends boyfriend, Im already tingling when I think about feeling his cock between my thighs... How am I supposed to confess the whole thing to Lisa now?