66M Inadvertent Threesome

In college I had hooked up with a girl and was fucking her doggy style when there was a knock on my door from one of my roommates. I responded that I was busy but he opened the door anyway. Without asking the girl I was pounding invited him over and had him drop his pants. She started sucking his cock while I continued to fuck her from behind. I'll be honest and share that it wasn't a turn on for me. I've never had the pleasure of a FFM although I did get naked with 2 female friends in a hot tub one night, one of whom I had been with before. We were all in committed relationships at the time and didn't feel right about cheating on our partners.