Don't get too short sighted. The chances of married guys staying married are less than half. The odds are sooner or later that guy that is a friend will need you when his marriage turns to shit. That's what friends are for, to celebrate the good times and to help in times of need. Friendship should be the "long term game". "Short term" friendship mostly ends up one person using the other, that's not friendship. A good friend doesn't have to be in constant contact, but contact should be mutual. It's best to show others you can be a good friend.
Being single around married couples can be awkward, I try to avoid this, (most men will try to avoid you being there also). I also don't mind being alone.