The reader really begins to identify with the Loisels when Mathilde discovers that she has lost the borrowed diamond necklace.
She removed her wraps before the glass so as to see herself once more in all her glory. But suddenly she uttered a cry. She no longer had the necklace around her neck!
This is the way these things happen. Everyone has had the experience of losing something of value and suddenly discovering that it is gone. It brings out a number of emotions--fear, disbelief, bewilderment, shock, dismay, maybe even panic. The Loisels go through a whole spectrum of familiar thoughts, feelings, questions, speculations, and apprehensions, all of which are perfectly depicted by Maupassant. No doubt, like most of us, they keep looking in the same places, hoping that somehow the missing item will be there even though it obviously wasn't there before.
"You're sure you had it on when you left the ball?" he asked.
"Yes, I felt it in the vestibule of the minister's house."
"But if you had lost it in the street we should have heard it fall. It must be in the cab."
"Yes, probably. Did you take his number?"
"No. And you--didn't you notice it?"
They looked, thunderstruck, at each other. At last Loisel put on his clothes.
"I shall go back on foot," said he, "over the whole route, to see whether I can find it."
And the husband, although he must have already been exhausted, goes out on a desperate quest, knowing that his chances of finding a diamond necklace in the streets of Paris are practically nil. But he has to do something. He is hoping for a miracle. Meanwhile his wife stays behind, hoping against hope that her husband will miraculously return with the precious necklace. We too are hoping against hope that M. Loisel will find the lost necklace because we have been in a similar situation, although most of us have never lost anything as expensive as a diamond necklace.
Maupassant was a realist. The necklace was never found--at least by the Loisels. Perhaps some someone walking along in the dark had suddenly had their wildest dreams come true when they saw a diamond necklace lying right at their feet. When Cinderella loses her glass slipper at the ball, she not only gets the slipper back but gets the handsome prince along with it. That sort of thing never happens in a story by Maupassant.