In a short story by Maupassant, a young man is upset by the past infidelities of his mistress, a rather paradoxical situation since he came much later after the infidelities (and somehow benefited himself from them). I would like to identify that short story.
This is very reminiscent of a passage in the middle of Chapter V of Bel-Ami (admittedly a short novel, rather than a short story). This can be found on page 182 in the version of “La Bibliotheque Électronique du Quebec” which is available online.
Et Duroy, pour la première fois, songea à tout ce qu’il ne savait point dans la vie passée de cettefemme, et il rêva. Certes elle avait eu des amants, déjà, mais de quelle sorte ? de quel monde ? Une vague jalousie, une sorte d’inimitié s’éveillait en lui contre elle, une inimitié pour tout ce qu’il ignorait, pour tout ce qui ne lui avait point appartenu dans ce cœur et dans cette existence. Il la regardait, irrité du mystère enfermé dans cette tête jolie et muette et qui songeait, en ce moment-là même peut-être, à l’autre, aux autres, avec des regrets. Comme il eût aimé regarder dans ce souvenir, y fouiller, et tout savoir, tout connaître !...
In the English translation by Marjorie Laurie this is
For the first time Duroy was struck by the thought of all that was unknown to him in this woman’s past. She had assuredly had other lovers, but of what description? Of what social standing? A vague jealousy awoke in him, a feeling of hostility towards her, towards everything of which he remained in ignorance, towards whatever in her heart and her existence had not belonged to him. He glanced at her, stung by the mystery hidden within her pretty head, which at that very moment was perhaps thinking with silent regret of that other, of those others.
How he would have loved to peep and rummage in this memory of hers, and get at the heart of all its secrets!