I read this short story only about 4 or 5 years ago (a bit "before Covid"), probably in a collection.
The pages of a manuscript are found on a table of a café next to an empty coffee cup. In the manuscript a man relates recent events that happened to him.
He had a difficult relationship with his wife. At some point, he and a friend both have an affair with two unmarried girls which were friends of each other. He had remorse and he told his mistress that he wanted to stop their relationship. But then things again go for the worse with his wife and he decides to see his mistress again.
Both girls live in the same apartment building where one cannot call the apartment directly, but only call the concierge who then calls the apartment. When he calls that evening he is told she just went out.
He cannot call again that evening, so he tries to reach her at her workplace the next day. He does not remember the phone number, only the name of the magazine for which she works. But he cannot find the name he remembers in the directory. He decides to go there, he remember the address. But where the offices of the magazine were, it is a totally different business.
He calls again the concierge of her apartment building, but he is told no-one of that name lives there. And the concierge denies having said the evening before that she had gone out, implying that she did live there. He asks for her friend, and is told that no-one of that name lives there either.
He calls his friend, to ask him if he knows where his mistress now lives. But the latter denies ever having had an affair, and any knowledge of the place where the first one claims they both had that affair. The hotel where it happened also denies any past reservation on the day he indicates under either his or his friend's name.
When he gets home, his wife is not there, nor any object belonging to her. Going through pictures he found in a drawer, he finds that though he can see himself, she has disappeared from all the pictures where they were together. (This reminded me of pictures in the movie "Back to the Future"). Also there is no trace of his friend on pictures he remembers being with him.
He calls his friend again, but the operator tells him the number does not exist.
He goes to a bar and writes down all these weirds events. The manuscript ends with a sentence about him drinking coffee.
IIRC The waiter does not remember having served the cup found next to the manuscript.
