The Lady with the Dog by Anton Chekhov (1899)

In a Yalta hotel room a woman weeps over what she has just done, sure she is ruined, and the man beside her cuts a slice of watermelon and eats it, unhurried, while she cries. That is Dmitri Gurov at the opening: a Moscow banker who has had many such affairs and trained himself to feel nothing, who privately calls women the lower race and means it. Chekhov's quiet cruelty is to let this man walk back to his wife and his card games and his comfortable contempt, and then discover, weeks later, that he cannot stop thinking of Anna Sergeyevna and her little white dog, that for the first time in his life he is helplessly, absurdly in love. The terror of the story is not the affair. It is the recognition that love is real after all, and has arrived too late, in the wrong life, with no way to live it. The last page leaves them in a hotel room sensing that everything difficult is only just beginning, and that no solution is anywhere in sight.