Permission to have sex with someone else...?

I had a dream last night that my boyfriend had sex with another girl..in the dreamit wasnt cheating, it was actually like it was very normal, almost expected. We both knew the girl, apparently a very pretty girlfriend of one of his friends, and asked if she could 'borrow' my boyfriend when he got back (from work presumably), to which i agreed as seemed i was supposed to, but internally hated the thought. When he returned i told him he was required to go and do the deed with her. He was concerned if i was ok with it, to which i had to repeat it was fine, whilst being obviously sulky about it. Off they went. I was devasted. I woke up several times whilest having this dream, the final time i was crying and its put me in a rly bad mood. I dont feel this is like a cheating dream as there was no infidelity as such! What does this mean??