Why did Mathilde go to her friend's house and tell her of her distress?

Mathilde is going with her husband to the ministry ball. He had set 400 francs aside so that he could buy a new gun and go hunting in the fall. However, he gives the money all to her to buy a new dress. Mathilde, nevertheless, is still distressed as the party approaches because she doesn't have any jewels to wear with her dress. Her husband suggests fresh flowers, but she rejects that idea and says it doesn't do to look poor amongst rich women. Her husband then suggests she borrow a piece of jewelry from her friend Madame Forestier.
Mathilde thinks this is a wonderful idea and relates to Madame Forestier her distress at having no jewels to wear to the ministry event. Madame Forestier is sympathetic and tells her she can choose whatever she likes from her jewel box.