Fuck yeah, that's what I love to hear. It's one of those things you just can't replicate with an open relationship or ask for. If he had your permission, that would take away all the fun of constantly guessing if he's cheating and finding out what he says/does when he thinks you aren't looking. I'd bet your sex life has actually improved since he started cheating. I've cheated with boys while secretly keeping their bfs in the loop so they can get a first row seat to watching their boyfriends authentically cheating on them and not just some open relationship roleplay/cuckoldry. Funnily enough, in that kind of set up, they'd tell me their relationship improved and felt more exciting. That or they realized monogamy wasn't their thing haha.
A few years back, before Tumblr cracked down on porn blogs, I had an account totally dedicated to real amateur cheating and cheating encouragement/captions OC. Was called "Gay Cheaters" if you google it + tumblr and sadly there's only a fraction of the content still there, but surprised that any is still floating around. Was close to 100k followers before it got taken down and from what I could find at the time, there was barely any gay cheating/cuckolding related porn anywhere--which is why I made it in the first place. Had tons of guys messaging me about how hot it was and their plans to cheat or watch their bf get fucked by someone else. Even ended up meeting some in person and fucking them, their bfs or partner swapping my bf at the time. I like to imagine that I helped spread gay cheating as a fetish, in some small form or another, and love seeing it becoming more popular over time.
I'll post some of my stories and pics sometime if people are interested.