What is the conflict in the novel The Necklace by Guy de Maupassant?

I guess the conflict could be seen as man vs self - Mathilde allows vanity, selfish pride and envy to cause her downfall. She makes one poor decision after another all in an attempt to appear to be something she is not. She foolishly spends 400 francs on an elegant gown to wear to a ball and borrows a necklace from a wealthy friend because she cannot bear to be seen in the company of wealthy women and appear to be "beneath" them in class.

She wants to appear to be of the upper, wealthy class, though she belongs to the middle class. She is so preoccupied with her appearance and her wishes and dreams to be like the women of higher society that she spends her husband's savings on a gown and borrows what she believes to be a diamond necklace of great value - and she is a great success at the ball. She is sought after and admired and she has a wonderful evening. Then, in her haste to leave the ball and not be seen in her inexpensive wraps (in sharp contrast to the ball gown and necklace she is wearing - and to the furs the other women are putting on as they prepare to leave) she loses the necklace.

She and her husband decide not to tell Mme Forestier (the friend from whom she borrowed the necklace). Instead, they use all the money they have and borrow even more to purchase a replacement. This drastically alters the course of their lives and it takes them 10 years to pay off their debt. In the end, she assumes the responsibility for what she has done and submits herself to poverty to pay for the necklace. She becomes part of the lower class.

Once the debt has been settled, she says she is glad. However, Mathilde Loisel still dreams about the night she went to the ball and remembers how admired she was. So, whether or not she has truly learned her lesson about envy and appearances, we can only guess.