The theme of the story is the mixture of pain and love in the intergenerational conflict between mothers and daughters—and the difficulty, further, of truly knowing another person.
The story is told from the point of view of Mrs. Dietrich, who is taking her seventeen-year-old daughter, Nola, shopping. They are a well-heeled twosome, despite Mrs. Dietrich being divorced, and they can spend without thinking about it in an upscale mall with stores like Neiman Marcus. Nevertheless, the two can't seem to connect.
While we don't get to experience Nola's interiority, we can sense how she is pulling away from her mother, trying to grow up and become her own person. For example, she smokes a cigarette at lunch at the Creperie, openly differentiating from her mother, who has recently quit. She wants to go far away, to study in France, while her mother wants to keep her close.
Mrs. Dietrich does not understand her daughter, experiences anger at her daughter's opacity, and feels time passing by in a way that frightens her. At forty-seven, she doesn't want her daughter to leave her: she wants them to be close, but she doesn't know how to connect.
That Nola feels some of the same grief her mother does is suggested when Nola bursts into tears at the sight of the strange old woman everyone is avoiding. We never know exactly what triggers her sadness, any more than her mother does, but we do know that she needs her mother then—even if she doesn't know how to express it.
Point of view is crucial to the theme of the unknowability of another human being, even one you love. Like Mrs. Dietrich, we are left not fully understanding Nola.