Answer:
Madame Loisel drives the plot in two very important ways. Firstly, her dissatisfaction at her humdrum, middle-class life leads her to borrow what turns out to be a fake necklace. Mathilde believes that she's entitled to better things and that what she thinks is an expensive necklace is just the thing to express her exalted self-image. For Mathilde, it doesn't matter what you are; it's what people think you are that counts. She's so shallow, so incredibly vain and superficial, that she's convinced that wearing expensive jewelry will be enough to make people think highly of her.
Explanation:
