I’m currently in Chiang Mai as well. Haven’t been out to much in the old city, but I have seen a few Thai couples (gay and lesbian) around. It is nice to see. I was doing the Segway tour, and my guide tried to pick up some ladies on a motorcycle - all he saw was the pretty faces, but I saw how the lady on the back was holding on the driver... it was more than just hanging on (could have been close friends).