Central to the collection is the theme of "bad faith" or self-deception. In the title story, the protagonist Monique is a woman who has defined her entire existence through her husband, Maurice, and her two daughters. When Maurice reveals a long-term affair, Monique’s world doesn’t just change; it vanishes. Beauvoir uses the diary format to track Monique’s descent, highlighting how she initially uses language to "mythologize" her role as a perfect wife and mother to avoid facing the vacuum of her own identity.