My wife Stacy and I had never discussed cuckolding in our marriage and had a pretty regular, fun sex life. I realized that I would get turned on at nightclubs with Stacy when I would catch other men looking at her, trying to hit/dance on her. Stacy is a short, thick blonde with an incredible bubble butt that always gets stares wherever we are. When I drunkenly told her one night how hard it made me to see other guys watching her she was surprised but not turned off - and asked if id like to see her dance/grind with other guys. I told her yes and for the next month or so I would sit at the bar and watch her do just that, some guys would get very handsy with her but things never progressed too far. Our sex following these nights was incredible as she was always turned on by her interludes with other men. One night our conversations turned to watching her fuck someone else. She was not receptive to just meeting a guy in a club as she didnt think she could go through it if there wasnt a connection. This led to us downloading Tinder, and getting fairly quickly an exorbitant amount of matches as she would spend a couple hours each night swiping away. We had a few good conversations over a period of three weeks but there was a clear conception with one guy, Mark - who is 43, divorced, and has had experience with couples. I was a little surprised she went with someone that old, but they would text/talk on the phone/etc constantly and Stacy really found him attractive. We agreed to meet at a bar/club we both like - and Stacy and I made a reservation at a hotel within walking distance downtown in case things went exceptionally well. Mark was very polite and charming, a tall, thickly built guy - he said he was an ex-lineman in college. Drinks flowed and they became more and more flirty, eventually heading to the dancefloor and then to a position where Mark had his back to the wall and Stacy was grinding on him. I watched from the bar and was beyond turned on while also feeling rising anxiety as I could see Stacy was totally into him. It was after midnight when Mark came to the bar, sweaty and grinning. He asked how I felt about things, I said good. He said that Stacy had told him we had a hotel and asked if he could take her there. I nodded in the affrimative, and then he grabbed my arm firmly and said "No man, I need you to be sure about this. She's been rubbing my dick for the past hour and I really need to get off". It was at that moment, as they say - things got real. My heart was pounding out of my chest and I said i was sure about it, but i doubt either of us really believed it. Mark ordered me another drink and said "we are going to walk over - finish this drink, then come - ok?" i nodded and watched him take Stacy's arm and walk off. I have never been more horny and scared in my entire life, its an emotion I cant begin to put into words. I arrived at the hotel probably 25-30 minutes later. Went to the room and walked in, the layout was door into "living room", small hallway with bathroom, then bedroom - anyone familiar with an embassy suites should be able to visualize the room. Everything was pitch black and I could hear murmuring and motion coming from the bedroom, i stood there for a minute listening, letting my eyes adjust before stripping down. I walked to the hallway and stopped right at the threshold to the bedroom and leaned against the wall where i could see in - I had no idea if they were even aware I was there. Mark was on his knees on the bed in between Stacy's legs, opening a condom and putting it on... he said "are you good?" and Stacy breathlessly said "yes, fuck me" - i felt an emotion ive never felt hearing that.. I watched him pushing into her and heard her groan and tell him to go slow. He obliged and started to pump in and out of her, I could tell by how his hips were moving that he was pretty well endowed - and this was confirmed by her deep, guttural moaning as he stroked. As he picked up speed she started to moan louder - it was the hottest thing ive ever seen or heard. He pulled out and told her to turn over, and he stood by the edge of the bed. He slapped her ass playfully and "damn i love your body". He saw me leaning against the wall and said "this what you wanted man?" I weakly replied "yes". He slid into her from behind and said "good, youre a lucky man". He started thrusting into her doggystyle, her thick cheeks slapping off his body - Stacy's face in the mattress moaning loud. He grabbed her hair and pulled back so she was arched up on her hands before slapping her ass hard, Stacy screamed "oh fuck!" he said "fuck yeah, you gonna cum on this dick?" and she moaned in the affirmative for probably 30 seconds before saying "shit i'm gonna cum". I watched her shudder, body quivering and falling prone on the bed before letting out a deep moan as Mark fell forward onto her, still pistoning up and down. I tried to resist but couldnt and sprayed the wall in front of me - moaning loud. Mark followed shortly after, pushing deep inside her and having his own orgasm. He stood up and lightly slapped her ass again and said "Fuck you guys are so hot" she rolled over, spooning a pillow and said "so are you" in a purr. I went in the bathroom and wiped myself off and came out to him pulling his jeans up, holding his button-up in his hand before putting it on. He slid his shoes on and walked me out to the living room and said "please call me if she needs this again" and then left. Sorry for the length. Given the cultural acceptance of this or lack there of - I am always open to discussing our experiences with like minded folks - SCD84 on kik if interested.