This is a true story, which occurred many years ago with my ex-wife. We had been married about 2 years. We lived in a one-bedroom apartment.
We had a married couple as friends, with my ex was best friends with Carol, the female part of the couple. Carol had confided in my ex that she and her husband were getting divorced. Carol was very distraught about it as they had a baby they had.
My ex asked Carol to come over for the weekend to get away, relax, and have some fun. She and her daughter lived with her parents at this point, due to the break-up. Carol's parents kept Carol's daughter for the weekend.
Carol came over on a Friday night and we went to dinner and had some drinks. We arrived back home and drank some more. We were all feeling pretty good, and my ex said she was going to take a bath.
I was playing a video game in the living room, and I thought Carol was in the bedroom. Soon I heard them laughing and giggling and I went to see what was going on.
I saw both girls in the tub, with my ex in front of Carol. Carol was soaping my ex's tits and rubbing them very erotically concentrating on the nipples. Her nipples were very hard and Carol was tweaking them in her fingers with the soap.
I do want to mention, after we were first married, I came home early from work one day, and found my ex naked on the bedroom masturbating to my Hustler magazine's pictures, of women! I asked her what was she doing, and she was embarrassed. She said she wanted to see what was in these magazines and found them pretty exciting.
I asked her if the models bodies excited her. She said she was mainly looking at the tits and the nipples. It was the first I suspected her of being attracted to women.