'A man ought to be just as courteous after marriage as he was before.'
'So he ought, but he never is. Possibly, there's some reason we don't know about,' said Wimsey. 'I've asked people, and they generally just grunt and say that their wives are sensible and take their affection for granted. But I don't believe women ever get sensible, not even through prolonged association with their husbands.'
From The Unpleasantness at the Bellona Club, by Dorothy L Sayers, chapter VIII.