•Why it earns a slot
Why it earns a slot: it is the story that proves Chekhov invented the modern non-ending, an affair treated as neither sin nor triumph, just an unresolved problem two adults carry into an unnamed future.
A married bank clerk starts a Yalta fling to kill time and ends up trapped in the first real love of his life, with no idea how to live it.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.