My girlfriend and I used to go to the gym together twice a week. It was one of those places where a coach personally trained a small group of people. One time, there were only four of us, and a new trainer was leading the class. As professional as he tried to act, I couldn’t help noticing him checking out my girlfriend’s ass during certain suggestive exercises, or her tits when she bent down. This wasn’t anything new to me—I always see men turning to look at her when we’re out together, even some of our friends. She’s sexy and attractive, so it’s natural. But she isn’t very aware of men staring at her, so after class I told her what I had noticed about the trainer. She was surprised, but also excited. She admitted she found him attractive, though she hadn’t picked up on any signals—probably because I was there. That night we decided she would start going to the gym alone, so she could flirt with him freely and see if he was interested, without me being there as a barrier. We even talked about what to do if he asked about our relationship. We agreed she could just play it off like she was cheating on me. Lying about it made the whole scenario even hotter for me, so we decided that was the best way.

From the very first session she went alone, he made his intentions obvious. He gave her special attention, watched her closely, made conversation. After one class they talked for a long time and then followed each other on Instagram. Seeing their messages made me go crazy—I was finally watching my fantasy come to life. The idea of my girlfriend being that interested in another man, giving him her time, was incredibly exciting. On top of that, it was one of the most cliché fantasies ever: your girlfriend fucking her gym coach.

Things escalated quickly. They started texting constantly, and not long after, he invited her out on a date. We agreed she would decide how far to take things depending on how comfortable she felt. I remember receiving the message: “I’m with him now.” I felt a huge pit in my stomach, my heart pounding in my chest, anxiety I couldn’t control. I knew I couldn’t bother her during the date, couldn’t send too many messages, so I just sat at home, waiting for her to update me. Hours later she texted that things were going well and she was having fun. A couple of hours after that, she messaged me that she was on her way back. She told me all the details of what had been a normal date until they left the bar and started kissing. They were both so turned on that they went to his car, but since there were too many people around, they drove somewhere more private. She told me she could feel how hard his cock was through his pants while he groped her tits over her blouse and slid his hand inside her pants to grab her ass. When she touched his cock, he guided her hand inside his pants so she could feel it properly. He was rock hard, leaking precum, and she started stroking him slowly while he kissed her tits and squeezed her ass. She could feel his breathing getting heavier, but she stopped before he came—she likes having that control. He tried pushing her head down, wanting her to suck his cock right there in the car, but she stopped him. She admitted to me that she had thought about it, that she really liked his cock, but it just wasn’t comfortable in that space.

They kept sexting at night, trading nudes. At the gym, when there were people around, he would grab her ass discreetly when passing behind her. During squats, he pressed his cock against her so she could feel it. After training, they would sneak to a corner with no cameras to make out and touch each other. She told me that people at the gym even thought they were a couple.

After a few weeks, it was time to talk about when and how she would fuck him. The plan was simple: they’d go on a date, then come back to our place to have sex, while I went out with friends. She’d let me know once he was gone, so I could come home, eat her freshly used pussy, and hear all the details. The only rule was condoms for safety—other than that, no limits. In fact, I wanted her to make it as dirty as she wanted.

That night, I thought being out with friends would distract me, but it didn’t. My phone became torture. I couldn’t stop checking for updates: “Everything’s good” halfway through the dinner, then “We’re going back to the house”, and finally the message that hit like a truck: “I just fucked him.” The fantasy was real now. Another man’s cock had been inside her. Another man had claimed my girlfriend, he had made her his. I wasn’t regretful—but I was in shock. I rushed home as soon as she told me he had left.

When I arrived, her clothes were still scattered on the living room floor. She was waiting for me in the kitchen, in sweatpants and a t-shirt, makeup ruined, lipstick faded, hair a mess. She looked nervous, asking if I was okay, if she had done the right thing. I hugged her first—she didn’t smell like herself. She smelled like sex, sweat, and his cologne. When I kissed her, she felt foreign, not mine anymore. And then she said: “Don’t my lips taste like cock? I sucked him a lot.” I lost it.

She told me everything. They had started kissing in the living room, him grabbing her ass hard, spanking her while sucking her tits. Then they went upstairs. He undressed, pinned her to the bed, and shoved his cock down her throat. She felt it sliding deeper and deeper until he was face-fucking her, holding her down, making her gag. She thought he was going to cum in her mouth right there, but he pulled back, put on a condom, and mounted her. She told me how amazing it felt to have a different cock inside her, to have a different man fucking her, feeling his muscular arms, his big masculine body on top of her. He lifted her legs onto his shoulders, fucking her hard. Then stood her up and bent her over the bed, holding her wrists tight so she couldn’t move while he pounded her harder and deeper. His cock was bigger than mine, and she wasn’t used to being fucked that rough and they switched positions. He then had her lie face down, lifted her hips, and slid back inside her. That position drove him crazy—she knew how good her ass looked. He spanked her hard, squeezing her cheeks while she moved back against him. She knew he was close, and then he pinned her tight, told her not to stop moving until he finally exploded inside the condom.