Quite a few things, but the primary thing is people I once got along with but for some reason don't anymore.
For example, a few weeks ago I was at a party where I encountered my ex-girlfriend (and given the nature of our relationship I use that term loosely). I haven't spoken to her in a long time, and figure that we will probably have a lot to talk about. I don't think I've been so uncomfortable in my entire life. We really should be able to talk but nothing happened. I was pretty much squirming on the spot for a few minutes till I slipped away into the crowd. So yeah, anyone I once got along with, but no longer do.
For example, a few weeks ago I was at a party where I encountered my ex-girlfriend (and given the nature of our relationship I use that term loosely). I haven't spoken to her in a long time, and figure that we will probably have a lot to talk about. I don't think I've been so uncomfortable in my entire life. We really should be able to talk but nothing happened. I was pretty much squirming on the spot for a few minutes till I slipped away into the crowd. So yeah, anyone I once got along with, but no longer do.