discuss how Madame Loisel in “The Necklace” thought things appeared one way but discovered that it wasn’t true?

Mathilde thought that "happiness" was being perceived as a glamour girl. She sets all of her expectations on one night at a fancy ball using her borrowed necklace as her main source of external validation. Although she appeared happy, her joy was empty and as fake as the necklace she is wearing. It takes losing the necklace and sacrificing her youth working to pay it back that Mathilde finds the real meaning for happiness in life.