Femdom is one of the most incel fetishes there is. People don't talk about it too much on here (likely because they'd get mocked) but back when I was on r9k there were threads about it everyday. I think it's because incels (legit sub4 incels) grew up getting insulted and mocked my girls, so that's one of the only fetishes they can mentally insert themselves incel.
It's probably a similar situation with literal cuckolds. They probably got cheated on a lot and their girlfriends/wives aren't attracted to them, so they end up fetishizing this.