My wife and I started in college. One of my ROTC buds (Lou) lived in an apartment walking distance from ours. Lou was a true chick magnet. He and I, also, played intramural sports, together, so I got to see him naked when he and I would shower after practice. He had one of the most lean, muscular, sculpted bodies I had ever seen. He also had a much bigger cock than me. I noticed that his cock in a limp state was bigger than my little penis in a fully erect state, lol. I could tell he was very proud of his cock, because he would always face me, giving me a very good view of it.
When he would come over to our apartment, I could see the attraction between Lou and my wife (fiancée at the time). They would literally flirt with each other right in front of me. I found myself starting to fantasize about the two of them having sex.
One night, my fiancée were talking about Lou and his success with women. She had had a few glasses of wine and she asked me if I had ever seen Lou's cock. I told her "yes" because I see it all the time in the showers. Then, she asked me if his cock was big. I chuckled and said "It's huge." And, I went on to tell her that his cock in a limp state is bigger than me in a fully erect. I started giving her more detail. I told her that he was cut and that even his balls were huge. She giggled a little and said: "I thought he might have a big cock because the bulge in his jeans is so big."
Ironically, the next semester, the two of them had a class together. She asked me if it was ok if they studied together. To which, I fully agreed. After the first week of class, she told me that they were going to study at his apartment because the student union was too noisy and the library was too crowded. I new Lou didn't have a roommate in his apartment, but I didn't make any mention of that.
My fantasies of Lou fucking my fiancée with that huge cock of his were running wild in my head. It was confusing to me because I knew I was supposed to be jealous. Instead, I was playing dumb to all of the clues and even making it as easy for my fiancée to fuck Lou as much as she wanted.
The arousal and curiosity was driving me nuts. So, one night, when she was at his apartment studying with him, I decided to take a walk. I knew, exactly, where the window to his bedroom was. I was hoping to either see something or hear something. Sure enough, as I approached his window, I could hear moaning. Then, I noticed there was a gap in his window blinds. I peeked in and there she was, on top of him, riding his cock. After the quick peek, I kept moving because I was afraid someone would see me peeking in his window. My little dick was throbbing like never before.
As I turned to head back to our apartment, I took a good look around the complex and I didn't see anyone. So, as I passed his window a second time, I decided to take another peek. This peek was a little longer and I got a very good look. I wasn't just amazed at the length and thickness of his cock, I was amazed at the ease she was having consuming the entirety of his huge cock. Literally all the way down to his huge balls. I could also tell he wasn't using a condom. He was fucking her bareback.
I wanted to keep watching, but I knew I couldn't. As I walked back to our apartment, I unzipped my jeans and started stroking my little penis.
Although it was confirmed that she was cheating on me, I continued to play dumb. I wanted his huge cock in her pussy as much as possible.
After a couple months, their affair got exposed. Lou, actually had a girlfriend and she found out, somehow, that Lou was fucking my fiancée.
I figured my relationship was done. However, she begged for forgiveness. She confessed to everything. At that moment, I decided to make some confessions, myself. I realized I didn't have anything to lose, since I thought I was going to lose her anyway.
I told her about the arousal I got from her fucking Lou and that I had known about it for months. Then, I really shocked her when I told her that if she still loved me and wanted to marry me, she was welcome to continue fucking Lou as much as she wanted. Now, it was a very confusing time for her, me and Lou.
The next week, or so, was pretty quiet, but we continued to discuss it. I told her that I would love to watch her and Lou fuck and that maybe we could make it a threesome. She and Lou agreed to give it a try.
The first threesome was awkward, but it went well. The second one was better, then the third, fourth, etc. Eventually, I went down on her right after Lou pulled out of her pussy. She giggled and said "are you sure?" Lou grinned at me and said "that's hot as fuck." She was surprised I would do that, but she loved it.
The threesomes were evolving into me watching more than participating with me cleaning and sucking his cum out of her pussy. Also, Lou was spending more and more time at our apartment. So, we decided it buy a king size bed that would fit all three of us. After we did that, I asked my fiancée how she would feel about Lou moving in with us. She got this big grin on her face and said "really?"
To shorten the story, we became a poly threesome. Only Lou's cum was allowed in my fiancée's pussy and stomach. This lasted until we graduated and it set the course for the lifestyle my wife and I enjoy to this day.