I usually reserve the term for men that are acting county.
My wife and I rarely argue and never resort to name calling......well almost never. Early on when having a minor argument my wife called me a "dummy" so I retaliated with calling her a "cunt". She just started laughing and asked "wtf?" so I explained that I believe in full and immediate escalation. No more name calling.
As much as I love the word cunt and use it frequently I don't think I've ever called someone a cunt to their face. I did say fuck you to a girl I was kinda friends with at work and she went in her office, closed the door and cried. I was shocked cause it didn't seem like a big deal to me.