also, I never regarded my partners as property, so really I just don't get it as an insult
Well, I mean, if you enjoy watching your devoted partner being fucked by someone else, then I guess you wouldn't see it as an insult...
If my devoted partner was being fucked by someone else I'd kick them the hell out of my house and not really care about the insult, as I'd be happy to have parted with such a piece of shit of a human being.