I had a couple of different experiences on both sides of the cuck equation and it planted the seed, which later led me to this fetish. Sorry its long but its sort of a 3-part story haha
In HS and through college I dated a pretty vanilla girl who I got along with super well but who seemed to have no sex drive of her own. She was submissive and let me do whatever I wanted but never initiated anything, even a kiss. It got pretty boring.
Meanwhile, I was friends with a girl who was a sort of evil temptress, always flirting with me and teasing me to the point that something was about to happen, then would stop. Well, one day it didn't stop and we ended up being FWB for several years while both dating other people. I felt like she wasn't long-term GF material because, ironically, I worried she'd be unfaithful. She dated a guy for years, who she eventually married but she kept fucking me and I thought it was super hot that this girl was such a horny slut she needed two men.
Slutty girl moved away but we kept in touch and she, told me her husband knew I'd fucked her and during sex, he would ask her how she liked getting fucked by my big dick and make her tell him how she wished I'd fuck her again... ol, at the time I thought it was pretty weird. The husband eventually coaxed her into being a hotwife and she would tell me about her escapades. So there was that...
I eventually broke up with boring sex girl and met a new girl who was super hot and horny but she had a kid (I guess that's what happens when you're a wanton slut). I was just not into the idea of raising another dude's kid but I couldn't stop fucking this chick. She got mad that I couldn't commit and threatened to start dating other dudes. A week later, she announced she was going on a date. I sort of panicked and asked her not to, which was unfair, since I was not about to get serious with her. She said nothing was going to happen but she felt like it was too late to cancel. Later that night, she called and told me they'd fucked. I felt sick and jealous but also horny. It was the first time I'd experienced that. I told her I wanted to see her and she was surprised, as she figured it was over but she came by and, sure enough, we fucked. So I guess it was like my first re-claiming. Oddly, things sort of flipped around, where she started seriously dating this guy but she would continue to come over and fuck me. I enjoyed the fact that she made her boyfriend wear condoms but let me cum in her pussy. I really got off on what a dirty slut she was and how she'd return to her boyfriend's place with a cum-filled pussy.
Eventually I moved on and several girls later, I met my now wife. We dated for 8 years and broke up a couple times mostly because I kept feeling like I wasn't ready to settle down and wanted to be single again but I could never stay away from her for long. The final time, she broke up with me because I wouldn't propose and was so mad / had sort of given up on me ever committing, that we stayed apart for 3-4 months. While we were apart, I agonized on the thought she was propably hooking up with other men. Every weekend I'd be out at bars thinking "I bet my ex is going home with someone right now to get fucked" and I'd feel jealous and sick but my dick would get hard. I ended up masturbating, imaging her getting fucked...
Weeks into the breakup, she told me I could come over and get some stuff she had. We ended up hanging out and she said I could stay the night but she wouldn't let me do anything beyond hold her. The next day she said she was still too angry with me and she felt like she couldn't get past it, that things were over and she didn't want to talk anymore.
Two months passed and I eventually convinced her to meet me for dinner. I proposed and we got engaged and ended up having sex that night. At some point I'd asked her if she'd been with anyone else to which she said, she had just dated a few guys and one of them kissed her at the end of the night but that was it.
I knew that was bullshit because my wife is a very horny girl and she had been very mad at me / basically said things were over for good. For years I would occasionally imagine what probably really happened and get hard, sometimes masturbate. That led into my watching cheating and hotwife porn.
Years later, she finally admitted the truth, incrementally over a couple occasions after having had some drinks. First the story was, she had dated a guy for a while and they had sex (couldn't remember how many times, so probably a lot) and she had danced and made out with another dude at a club. Of course, later, found out she had also fucked the guy from the club.
It made me a bit jealous but mostly turned on at this point. Looking back, I realized, the night I slept at her place, after we'd been broken up, she must have already been fucking other dudes. I also found out, she told the guy she was dating that she was going meeting me for dinner, the night we got engaged and he begged her not to go. After I proposed to her, we went back to my place and fucked all night... so I always wondered how long it had been since she fucked the other guy, whether it was days or hours. Another part I really enjoy thinking about is that my then "ex-girlfriend" was still in a relationship when she accepted my ring, cheated on her boyfriend with me, then the next day, after ...... at my place, she went back and broke up with him.
I posted previously, if you wanted to know, about the episode where she finally admitted she'd fucked the second guy and the hot sex / dirty talk that followed:
https://www.wifewantstoplay.com/threads/fucked-on-break-up-got-wet-telling-me-later.29399/
All these experiences inevitably led me more and more into enjoying MFM and hotwife porn. I'm not into the humiliation aspect but I find that I really get off on women being naughty sluts. I confessed this to my wife a few years ago and it was not initially well received but a lot of progress has been made since then. Whether she'll make the jump and ever actually do anything is yet to be seen...