Do you think infidelity is the only explanation for Mme. Lantin’s possession of the jewelry. Is she in some sense a “kept” woman (who thereby managed to keep her husband in comfort)? After all, the author never spells this out. If you agree, why doesn't the author come right out and state this?
This is an excellent question. Maupassant does not tell the reader whether all the jewelry owned by Madame Lantin came from a single man or from many different men. But this subtle author apparently wished to leave the question a mystery. The story is told from the husband's point of view. He would not necessarily want to know any of the sordid details. It was bad enough for him to realize that his wife had deceived him consistently for years. It would seem that you are quite correct in surmising that Madame was, in a sense, a kept woman. The jewelry she collected is all very expensive. She could not have had a number of lovers who all could afford to lavish such presents on her. It is far more likely that she had one very wealthy lover who was able to adorn her with such tokens of his love. And it must have been genuine love for him to give her so many precious gifts over a long period of time. Nothing would have been gained by the author's naming this invisible figure. And Monsieur Lantin does not want to know.
When Lantin sells the first item, a necklace, to the jeweler from whom it was originally purchased, it is obvious that the jeweler knows the name of the man who originally bought it. In fact, this jeweler probably knows who bought all the jewelry Lantin inherited from his wife, because it is extremely likely that the man who bought the necklace would buy the other things from the same shop. Lantin has no trouble selling all the jewelry to the same jeweler because that man knows them all and knows what prices he sold them for. The following exchange between Lantin and the jeweler shows all this and also shows that Lantin does not want to know the purchaser's name.
As he was about to leave the store, he turned toward the merchant, who still wore the same knowing smile, and lowering his eyes, said:
“I have — I have other gems, which came from the same source. Will you buy them, also?”
The merchant bowed: “Certainly, sir.”
Monsieur Lantin said gravely: “I will bring them to you.”
The large diamond earrings were worth twenty thousand francs; the bracelets, thirty-five thousand; the rings, sixteen thousand; a set of emeralds and sapphires, fourteen thousand; a gold chain with solitaire pendant, forty thousand — making the sum of one hundred and forty-three thousand francs.
Clearly Monsieur Lantin has a golden opportunity to find out the name of the man who bought all those jewels, because it is obvious that they were all bought from the same jeweler by the same mysterious man. Even if the jeweler refused to identify the customer, it would at least show that Lantin really wanted to find out who it was. But Lantin does not ask because he doesn't want to know. He is humiliated, but he is taking the hundred and forty-three thousand francs and swallowing his pride.
Madame Lantin was not promiscuous. She was unfaithful to her husband, but at least she was only unfaithful to him with one man. Somehow that seems to make her more respectable. That other man must have given her cash in addition to the jewels.
[Lantin] was unspeakably happy with her. She governed his household with such clever economy that they seemed to live in luxury.