I mean, there can be a sexist element to “cucking" fantasies. In that the appeal to the cuckold isn’t compersion, the idea that his female partner is truly happy and in love and he’s happy for her. Who the “bull" is doesn’t matter, it’s more the fact the bull exists that is the turn on. Sometimes what’s the turn on is that the “bull" has physical qualities that the cuck feels he lacks, like a bigger dick (and often these men in porn are black which brings an uncomfortable racist element in). So in that sense both the bull and the “hotwife" have the potential to be objectified, it’s not a genuine relationship or an encounter that the “hotwife" may have chosen for herself if it wasn’t her cuck’s fantasy.

It’s possible to do partner sharing in a way that isn’t sexist or objectifying but in that sense it’s more polyamory or swinging rather than cuckolding fetish.