Why is the verse from the George Gershwin song "They Can't Take That Away From Me" that Kay begins the book with so significant to Millie's life?

The verse from the George Gershwin song "They Can't Take That Away From Me" that Kay begins the book with is so significant to Millie's life because in the wake of her husband Joss Moody's death and the revelation that Joss had a woman's sex organs, Millie feels like her marriage to Joss has been misrepresented, misinterpreted, and upended. The Gershwin song lyrics speak to a feeling that someone will always be able to hold on to affectionate memories from a cherished relationship.