> "saying you’re done with sex permanently and your partner should be too"

If I could not do anymore something that makes my partner happy, the least I could do would be saying "Please do it with someone else". Because I care about her and I want her to be happy. (BTW, I've read about this actually happening in some loving couples)

Saying instead "I'm done with sex and you should too" is pure childish selfishness. It means "I don't care in the least about your happiness", and therefore "I don't care about you".

And for anyone complaining that sex doesn't matter so much, what about someone saying to his/her partner: "I'm fed up with talking; I won't talk to you anymore, and you shouldn't talk as well". Would you find it acceptable...?!?

Same thing.