Hi! This might be a good place to start. Also, Youtube and places like Pornhub have clips of scenes. https://www.imdb.com/search/keyword/?keywords=cuckolded-husband
There is a Norwegian film called The Crossing (2004 i think) is pretty powerful. There is a scene that was really sad,but erotic, from the movie called Scandalosa Gilda from , I think, 1985 or 86. I hope this helps.