<human>: As in the title, he's 23 and I am 18. We've been together for about ten months and everything was going alright. Last night he decided he wanted to ask that before December (I don't see why December is a factor of this) if we could both sleep with two different people each. 

  I told him that I wouldn't sleep with another guy. Ever. I told him if he wants to fuck another chick so bad, then just do it.
He proceeded to tell me that a chick 'wants in his pants' and I'm sitting here at the moment  dumbstruck that he would say that to me. 

Now, backstory, I have some self-esteem issues. Don't think I'm good enough, good looking enough, etc. So I'm just kind of confused why he would tell me someone wants to sleep with him.

I don't really know what the heck to do or if this is a sign that he doesn't want this relationship anymore. (I can't really tell.) He's talked about marriage, went through all that crap. And now this. 

So. Is it wrong I told him to just go do whatever? Just to get him to stop talking about it?

Condense the text into a few key points
<bot>: Boyfriend (23) wants to sleep with other people. I, (18), gave him 'permission' even though it bothers the hell out of me.