M. Loisel is only a minor character, and Maupassant does not bother much about developing him. He exists because there was no way Mathilde can go to a ball all by herself like Cinderella. She needed to be escorted and needed an invitation. Also, there was no way that Mathilde could ever pay for the replacement diamond necklace herself. In those days her only feasible occupation was as a housewife. All she can do to help her husband pay for the necklace is to economize in every possible way, which includes doing all the laundry work and other hard household labor herself. Loisel earns and pays the money, but Maupassant focuses his attention on Mathilde, since it is her story and her tragedy. M. Loisel must be considered a static character, although his wife undergoes a profound character change over the years of privation. Maupassant takes pains at the end of the story to describe Mathilde's character change. She has lost all of her beauty and all of her illusions, but she has acquired strength and wisdom.
In literature, a static or flat character is one who does not change throughout the story; and, along those lines, a dynamic character is one whose ideals or personal mantras change because of circumstances or events extending from the plot. Thus. when analyzing Maupassant's leading male character in "The Necklace," one must ask the question if Mr. Loisel's character changes from the beginning of the story to the end. Mr. Loisel does not, in fact, seem to change. Life's circumstances due to the poor choices of his wife force him to endure ten years of hardship and sacrifice, but he remains stable to what his character represents throughout the story. Mr. Loisel, although the bread winner of his marriage, places his wife's desires above their own financial means; as a result, they suffer financial ruin for many years. The story ends after the ironic ending sheds light on the folly of the Loisels misfortune (due to misunderstandings and the lack of communication) so there is no evidence to suggest that either of the Loisels actually learned a lesson and changed their ideals or personal mantras. On the other hand, they did learn how to sacrifice their social lives and debt-ridden spending in order to pay back Ms. Forestier for the necklace they lost. This could be considered a type of worthy change of lifestyle in order to honor a debt. But again, there is no further evidence to show that they wouldn't fall back into their dream-filled ideals of what Madam Loisel "deserves."