What is the impact of having the narrator explain what Mme. Loisel and her husband each think?

The narrator's purpose in supplying us with two different perspectives is to further our understanding of Madame Loisel's self-centeredness. She is unable to think of anything but herself, whereas, her husband is unable to separate their dire situation from the rest of their life. He still has responsibilities to perform; his wife was too busy indulgong in a pity party.