I sure hope my girlfriend doesn't find out but if she hasn't by now I'm probably safe. Her 18 year old daughter (whom I've always respected) had her best friend staying with her for a few days. She's a very pretty girl, Hispanic, Asian looking eyes, a little chubby in the hips but a nice slim waste, I'd say 5' 1" and about 130lbs. The first couple of days she didn't pay too much attention to me but the night before this happened I took her and my girlfriend's daughter out for pizza and to the movies. During the pizza and afterward we kind of hit it off on some level. She had a wicked sense of humor and was into the Beatles, Bee Gees and other music that I really like that I never guessed she would be into. We got home and I said goodnight as i head for my girlfriend's room and our eyes kind of connected and she smiled and said goodnight. It reminded me of one of those eye contact moments you have when you're young and flirting but I didn't give it too much thought. I was there with my girlfriend, this was her daughter's best friend and there was a 27 year age gap though I do keep myself in shape and look much younger. The next morning my girlfriend had to be at work by 5am, I had the day off and my girlfriend's daughter had school that day (her friend had just graduated, my girlfriend's daughter still had another week, different districts I guess. I got up to make coffee and I was in my t-shirt and boxers, she was laying on the couch with her ear buds in. When I saw her I just kid of nodded good morning and she smiled back that same smile from the night before. I then went back to the room and started my shower. About a minute into my shower she knocked and poked her head in and said she had to pee really bad. I told her "go ahead, I'm washing my hair, my eyes will be closed." I'd just rinsed the shampoo when she got into the shower with me, butt naked. At that point I probably should have objected and told her to get out, this isn't appropriate but I guess you never know how you'll react to these situations into you're in them. I got hard instantly, started kissing her, she grabbed my cock, I started fingering her from behind. I turned the shower off, picked her up and carried her to the bed, ate her pussy, fingered her g spot until she came, she was a squirter and came multiple times, since she was clean I then flipped her over, ate her asshole for a few minutes, she loved it. I was dying to fuck her at this point and she wanted to be fucked, at this point the consequences didn't matter, it was all worth it. I was lucky and found a condom, my girlfriend had been operated so condoms are a thing with us but I just happen to find an old one tucked away in my wallet. I put her on her stomach, propped up her ass with a few pillows and straddled her ass and gave her a good fucking. She moaned throughout, she came a few times and then I finally came. We laid there cuddling for a while and talked about what happened. She said she was cool with it being a one time thing and promised not to tell. So far she hasn't and we haven't done it again.