Interestingly enough, Guy de Maupassant attempts to use a non-judgmental narrative style that bases the indirect characterization of his characters entirely on their actions. However, he cannot resist playing with words and attributing hyperbole and other allegory to specific dreams of Mathilde, her behaviors, and her thoughts.
The author also narrates and describes the actions of the characters under a light that reflects their personality flaws: they are either too simplistic or too complicated; too satisfied (the husband) or too dissatisfied (Mathilde). Since actions speak louder than words, clearly Maupassant wanted his characters to "do the talking" for him.
In "The Necklace", however, being a Realist novel, Maupassant manages to put some of this emotions on the surface, not necessarily criticizing Mathilde herself, but women in general. Marriage is also criticized, social relations, and the hierarchies that make up the social classes.
As far as criticizing women and marriage, notice how Maupassant already takes jabs at the two from the very start:
The girl was one of those pretty and charming young creatures who sometimes are born [...] to clerks. She had no dowry, no expectations, no way of being known, understood, loved, married by any rich and distinguished man; so she let herself be married to a little clerk of the Ministry of Public Instruction
The tone used is, therefore, is very ironic, highly sarcastic, and very indicative of several things:
- Women have no choice in society but to marry
- The lower classes do not often have "pretty and charming" daughters
- Marriage is a business transaction. No money, no good prospect.
- Clerks are "little" in value
- Being married to a worker of the Ministry of Public Instruction (Maupassant was one) is a lowly marriage option.
Throughout the story, we see many more examples of this tone and criticism of Maupassant. However, remember that he also juxtaposes the issues with his characters to their realities: there is very little people without resources can do when they face a situation. Money would have helped ease a lot of the situation. They did not have the money. Circumstances were less than optimal for them. Therefore, there is still a degree of compassion to be had that does not entirely put the character under a uniquely negative light.