Sharing a bathroom I don't even do with the spouse-I go in, door gets locked.
Many years ago, when I was single, I went with a group of friends to a large gay disco-so large, one dance floor, surrounded by bars, was for gay men and upstairs was a slightly smaller dance floor and bar for women. A third dance floor on the first floor was mixed. It was winter, so I had worn a turtleneck under a flowy-gauzy type shirt, but I was hot from dancing so I went into the ladies room. It didn't have doors on the 2 or 3 stalls, it had curtains and since I didn't want to waste a stall taking the sweater off, I stood in the lav section. As I'm changing out of my sweater, I hear in a very loud voice, "Hey! She's getting undressed in there!!!" and a rush of females came to the door!
My friend yells in for me, I yell out to her and the throng that I'm just taking off the sweater, hastened it up and ran out.
My only change in thought and deed: I won't change clothes in ANY restroom anymore