A while back, around November 2007, my 10-man raid leader disappeared. This was around the time of Zul'Aman's release. Prior to that I can't remember being so excited about raiding. I was looking up strats beforehand and we were doing well. So well in fact we had reached Zuljin (the last boss) right before our raid leader (and main tank) left.
There have been few times in WoW where I've been so disappointed. I had raided with this player for over a year if not more and poof he was gone. No one seemed to be willing to talk about it either. I know he came back eventually but that bridge was burnt.
Me? I eventually moved on, switching guilds now and again, but also making sure to explain my reasons why to those I was leaving behind. (It has never been about the players - but usually the schedule.)
The reason I bring this up is because recently I looked around and realized I was in another 10-man group that I was thoroughly enjoying and we're actually making decent progress.
The pessimist in me would usually say "and now I'm waiting for the broadaxe to fall". Instead I'm going to ride this wave for as long as I can.
It took a long time to get back to this kind of feeling, I'm not going to wish it away.
6 hours ago