[Reyoki]

My brother is about the same way. When he goes to play his games or Skype chat with his gaming buddies, he'll go into the other room and mute everything when someone else walks in the room. We can still hear him talking and swearing up a storm from the other room, though. I asked him about it once and he said he just doesn't feel comfortable gaming and Skype chatting with the rest of us around because he doesn't like to feel like he's being watched. He said it makes him feel really self-conscious. It could be the same with your boyfriend.

As Tiva and Uru have said, though, your best bet is to just ask him about it.