What is the theme in A Year by the Sea: Thoughts of an Unfinished Woman by Joan Anderson?

Marriage is a major theme in this book. "A Year by the Sea: Thoughts of an Unfinished Woman" begins with Joan's sudden realization that she was no longer happy with her marriage, and over the course of a year-long separation, she and her husband both redefined the role of marriage in their lives. They got married very young, and Joan reflected that ". . . many of us entered marriage as only half a person, expecting to be completed by the other." (Chapter 4, Riptide, p. 46) She came to realize that a healthy marriage must be a bond between two healthy adults, who build one another up, rather than weighing one another down. This was why it was so necessary for both her and her husband to have the chance to grow beyond their traditional, limited roles.