Roald Dahl wrote a short story called "Nunc Dimittis" (though Wikipedia states that it was first published in 1953 as "The Devious Bachelor"). The story is described here on Wikipedia: it essentially involves a troublemaking older woman falsely convincing the protagonist, Lionel, that his girlfriend, Janet, finds him boring; the protagonist then takes elaborate revenge on Janet, humiliating her in public. At the end of the story it is implied that Janet has poisoned Lionel in retaliation.
Why is the story called "Nunc Dimittis"? Again from Wikipedia, this appears to be the Latin name of a Biblical hymn, literally meaning "now let depart". What is the relevance to the story?