Memes

I know this is a digression from the topic but, what's with the word 'cuck'? I've never understood why people are called 'cucks' as an insult. My understanding is that it's short for cuckold and that's always seemed weird to me because if a guy gets cheated on by his partner I don't automatically think less of them for having that happen to them. There's another, I assume more modern, sense of the word where 'cuck' is referring instead to a fetish where a guy likes seeing their partner have sex with others. But like, if that's the sense of the word being used when someone is derisively called a 'cuck' as an insult then it makes even less sense than the more traditional meaning of the word because if they're in to that, then surely they're unlikely to feel particularly ashamed or upset about people calling them that because it's just... accurate.