In "The Necklace," how has hard work affected Mathilde's character? How has her attitude changed at the end ?

Hard work affects Mathilde's personality, physical appearance, and character in Guy De Maupassant's short story, "The Necklace." She is a dynamic character in this story that goes through several changes. 

Mathilde Loisel is described as a pretty young woman with delusions of grandeur. She is born to a modest family but covets social status and the respect that accompanies it. An example of her distaste for her station in life is contained in the following quote: 

"She had no clothes, no jewels, nothing. And these were the only things she loved; she felt that she was made for them. She had longed so eagerly to charm, to be desired, to be wildly attractive and sought after. She had a rich friend, an old school friend whom she refused to visit, because she suffered so keenly when she returned home. She would weep whole days, with grief, regret, despair, and misery."

Mathilde's husband, a lowly clerk she "allowed herself to be married to," comes home one day with an invitation to an exclusive event held by important people. He believes this will greatly please his wife, but she is not happy. She complains that she has nothing to wear, so her husband offers to give her the 400 francs he had been saving to buy himself a gun. Next, she complains because she has no jewels. Her husband suggests she borrow some from her old school friend, Madame Forestier. She borrows a beautiful diamond necklace from her friend to wear to the ball. At the ball, she is described as ecstatically happy, rejoicing in the attention she receives from men. She is charming, "quite above herself with happiness." She stays deep into the night dancing, while her husband dozes in a nearby room. 

When it comes time to leave, she is embarrassed at the wrap her husband has brought. She sees the other women with expensive furs and believes her own wrap will clash with her jewels and gown and belie her humble station in life. It is her vanity and pride that cause her to leave the party without a wrap, and she and her husband end up shivering in the cold without transportation. The tale is a bit Cinderella-esque in its description of Mathilde's gaiety at the ball, and when it is over, she is left without adornment in a shabby carriage that isn't allowed in Paris during the day.  

Mathilde doesn't notice the necklace is missing until they arrive back at home. Horrified, she and her husband concoct a plan to buy a new necklace to return to Madame Forestier without divulging the fact that the original has been lost. It is again her pride that causes her to make this choice, rather than admitting to her friend that the necklace is lost.   

Mathilde and her husband spend ten years working off the debt of thirty-four thousand dollars they incur by buying the replacement necklace.Mathilde changes physically in that time. The text describes her this way:

"Madame Loisel looked old now. She had become like all the other strong, hard, coarse women of poor households. Her hair was badly done, her skirts were awry, her hands were red. She spoke in a shrill voice, and the water slopped all over the floor when she scrubbed it."

Her character changes, as well. She accepts her lot in life and the responsibility to pay off the debt. Ironically, her pride, which would not let her tell the truth, also allows her to become everything she detested in order to pay off the debt of the replacement necklace. She honors this debt at all costs. Her servant is dismissed, she gives up her home for a modest garret under a roof. She has to haggle for everything she buys and accounts for every penny.  

When she sees Madame Forestier ten years later, she is finally prepared to reveal the true story of what happened that night. The debt has finally been paid, so she has completed her duty. She tells Madame Forestier how she has suffered in her efforts to replace it. She talks about her sufferings matter-of-factly, which is different from the beginning of the story. The littlest indignities were blown completely out of proportion in describing the way she suffered in the beginning.  

Rather than trying to climb to a higher social status, now, she accepts her fate in a lower social station than she had when she married. She is resigned, hardened, and matter of fact, rarely giving sway to the fantasies of her youth. She doesn't harbor bitterness or envy any longer. The story ends with Madame Forestier revealing that the necklace was not made of genuine diamonds, and was worth at most five hundred francs. The reader is not privy to Mathilde's response, and must make inferences about how she reacts to this news. But in the ten years since the necklace went missing, Mathilde has changed both physically and intrinsically. It's interesting to ponder how she may have reacted.