One could argue that Monsieur Loisel was relatively content with his life before attending the ball and spending the next ten years paying back debts in order to replace Madame Forestier's diamond necklace.
Before attending the ball, Monsieur Loisel appears to be in good spirits, which is evident by his reaction to the beef stew. When Monsieur Loisel uncovers the soup tureen, he declares, "Ah, the good pot-au-feu! I don't know anything better than that." By examining Monsieur Loisel's joyful reaction, one can suggest that he is relatively content and fulfilled with his humble lifestyle. He does not dwell on the things he cannot afford, which is exactly what Mathilde does on an everyday basis. In addition to Monsieur Loisel's positive disposition during dinner, he also illustrates his pleasant demeanor by announcing to his wife that they have been invited to an exclusive ball at the Ministry.
Monsieur Loisel's excitement once again indicates that he is content in life and easily pleased. Unfortunately, his wife's perception of their life could not be further from his because Mathilde is a superficial, ungrateful woman. Mathilde resents marrying a lowly clerk and feels entitled to a luxurious life. When Mathilde receives the invitation, she immediately dismisses the ball and laments about not having the proper clothes or jewelry necessary to attend such an elaborate event. Monsieur Loisel is disheartened by her response but agrees to make concessions to please her.
Tragically, Mathilde borrows Madame Forestier's diamond necklace and loses it. Monsieur Loisel ends up spending his inheritance and taking out numerous loans to replace the expensive necklace, which turns out to be a worthless imitation.