Mathilde is a woman born into the wrong class. She envies what all of her "well-to-do" friends have, which leads to her downfall. She is a malcontent who is never satisfied with anything. She looks at her home, her help, and her husband and sees only what is lacking--fine furniture and tapestries, many servants, and the richest men wooing her. When her husband reveals the invitation to the party, she whines that she has nothing to wear. When she gets an outfit for the party, she whines that she has not jewelry to match it. She is never satisfied.
Her husband on the other hand sees in his home and wife, all that he could ever want. He loves Mathilde and attempts to please her at all costs. He sacrifices his own desires to give her the money he'd been saving for his hunting rifle so that she can have a nice outfit for the party. He goes into severe debt to repay the cost of the lost necklace.