I had an ex start talking about doing a 3-some and it made me pretty sick. We had problems with sex anyway (me never wanting it, and him wanting it all the time.) I still remember him talking in his sleep saying, "We could have this girl I know come over....she's clean......it would be cool......" Ugh.....
I just wouldn't be ok with it. It made me feel like I wasn't enough for him. My current bf and I joke about it, but I know it would never happen and he'd never ask me, its just joking.
I just wanted to tell you I understand.....and man did your post strike a chord in me, sure brough back a painful memory, but I went through it so I could post to you years later and say I relate.
I truly do hope its a phase. I agree with what was previously said that maybe it would be good to talk to him about it in a non-intimate time and tell him you don't like it.
Hang in there and feel free to PM if you need.
~Rayna