What causes the Loisels' financial situation?

At the
beginning of the story, the Loisels are relatively poor. They are poor because Madame Loisel was
"born ... into a family of clerks" and had "no dowry," and because her
husband is only "a minor official at the Ministry of Education." Madame Loisel is said
to "suffer ... because of the poorness of her house." The walls of the house are
"dirty" and the chairs are "worn-out." Nonetheless, the Loisels still have a
"little Brenton girl" to do their "housework," so as poor as they may be,
they do not seem to be desperately poor.

In the second half of the story,
however, the Loisels are reduced to a more abject poverty. Madame Loisel comes to know "the
horrible life of the very poor." She is forced to dismiss the "little Brenton
girl," and take upon herself "the drudgery of housework." At the markets she has
to "fight ... over every miserable sou." Her husband, meanwhile, "work[s] every
evening ... and often, late into the night."

The case of this more
miserable, more desperate financial situation is a diamond necklace that Madame Loisel borrowed
from a friend earlier in the story and then lost. She and her husband live a life of abject
poverty for ten years to pay for the replacement necklace. Tragically, at the end of the story,
the Loisels discover that the diamond necklace was only an imitation.