Parties
I like people. I also like my solitude.
Even at small get-togethers, I do initial greetings and well-wishing. My small talk is down to 60 seconds. Even if it's non-stress like only listening to others talk, my peripheral vision is looking at the exits, estimating how long I should wait before making a retreat and exit, of course without announcing my intentions.
I went to a wonderful surprise birthday party for a member of my YMCA, a man who just turned 90. I know and like him a lot. I stayed for the "Surprise!", singing of "Happy Birthday", the group picture, and was gone 5 minutes later. I even skipped eating the birthday cake. All I wanted was to leave, get in the car, and drive.
I'm better with one-on-one with selected individuals where I don't think of how soon I can leave.