LadyBlue, that is a great observation. I was the same way. I somehow managed to meet people who drank more, or as much as I did. As long as they were around I was the more "normal" drinker. Funny how that works. Looking back, I wonder how many people were doing the same to me, hanging out with me because I drank more than they did. Yikes! Not that we weren't real friends, but it is different how you choose friends drinking vs. sober.
I think we also tend to be more introspective and withdraw when we quit, so we're not the ones calling making things happen anymore. If our friends were used to us making all the effort, and we stop, then there's not much left. It takes effort on both parts to continue the friendship, and it's harder if one is sober and one isn't.