I nominate The Sense of an Ending by Julian Barnes, which won the Man Booker Prize.
From Goodreads:
Tony Webster and his clique first met Adrian Finn at school. Sex-hungry and book-hungry, they would navigate the girl-less sixth form together, trading in affectations, in-jokes, rumour and wit. Maybe Adrian was a little more serious than the others, certainly more intelligent, but they all swore to stay friends for life.
Now Tony is in middle age. He’s had a career and a single marriage, a calm divorce. He’s certainly never tried to hurt anybody. Memory, though, is imperfect. It can always throw up surprises, as a lawyer’s letter is about to prove.
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