I think one of my correspondents is sulking. People sometimes do after having it explained to them in practically scholarly detail why they were wrong to take umbrage in the first place.
Funny business, sulking. It involves ignoring people, and not just certain people in particular but pretty much everyone, yet it strikes me as something directed not so much outwards as inwards: hiding away, brooding, nursing bruises to the ego. Or perhaps one should say that the sulker refuses to be dragged into any recognition that there is anything outward, so that inwardness becomes the universe. (Is it possible to sulk collectively? Can people with a shared grudge have a sulk-in? The Newton-Leibniz dispute has sometimes been called ‘The Great Sulk’—a term which also seems to have been connected to Edward Heath.) One resents a slight or the person who caused it; one broods over the slight; one sulks at nothing in particular. One just sulks.