Bittersweet: How Sorrow and Longing Make Us Whole is a book that can be challenging to categorize. For much of the first chapter, the book reads as a memoir in which Susan Cain narrates the relationship she had with her mother during her childhood into her young adulthood. She also discusses her love of the musician and writer Leonard Cohen and other sad music, and she offers many self-reflections throughout the entirety of the book. She reveals to the reader that she lost both her older brother and her father to COVID in the same year, and her presence in the book is generally consistent. Even as she interviews various experts in fields ranging from psychology to neuroscience to business management, her reflections on the interviews suggest that this is also a personal work for her.

One could also categorize this book as self-help, as ultimately Cain’s purpose is to offer readers insights that she has gained from probing into the mysteries of melancholy. She wants to teach readers How to Respond to Pain. She often uses the second-person, direct address to mimic a dialogue with the reader and guide them into their own state of self-reflection.