Sarah finds herself in a challenging situation that an adult reader can more clearly understand than the young readers, who are the book's target audience. Young Anna and Caleb spend the entire time wondering whether Sarah will stay, or if she will choose to leave them, because she misses the sea. Grownup readers will understand that Sarah's decision will not be predicated on whether she misses the sea, but rather on whether she will be allowed to be herself with this new family.
Wives in this era were legally considered property, and women in general were denied the voting privileges taken for granted in today's modern democracy. Yet Sarah is a remarkably independent woman for her time. One of her first comments to Papa is to insist that her cat be allowed in the house, instead of sleeping in the barn where Papa suggests. Papa offers no reaction to this comment, neither affirmation nor opposition. He and Sarah are both careful around each other at first, but this natural caution on Papa's part leaves Sarah to wonder if he will be a tyrannical husband or if he is a kind man in search of a true and equal partner.
The events that reassure Sarah are not fully comprehended by the children. When Papa agrees to teach her to ride a horse and to drive the wagon by herself, Sarah's worries are much appeased. She presses her advantage immediately by insisting that he allow her to help him fix the roof. Spurred on by the oncoming storm, Papa agrees, and is thrilled to learn she is every bit as good of a carpenter as she promised. Sarah is equally pleased that her skills are a plus in his eyes, because many men of that era might have felt displeased to find such ability in a woman.
Papa, however, is quite egalitarian for his day, sharing the cooking duties with Sarah even as she shares the plowing with him. In addition to his acceptance of her liberated attitudes, Papa also appreciates her femininity. He demonstrates this appreciation by burying the dead lamb for her, by picking her flowers to wear in her hair, and by the many other ways in which he shows his appreciation for her whimsical side. Papa has missed the loving warmth of a female presence in his life, and feels fortunate to have found such a strong and capable woman to provide it.
Sarah puts Papa to the test when she announces that she is going to town by herself. The children are upset, because she doesn't tell them where or why she is going to town. They assume she means to leave them. Sarah, however, is only intent on showing Papa that she has the right to go when and where she pleases without asking for his permission. When Papa offers no objection whatsoever to her plan, he all but seals Sarah's decision to stay. She can relax now that she knows she will be allowed to be who she is in this new home. Papa is offering her everything she left Maine to find, a home of her own, a loving husband, beautiful children, and the right to be in charge of her own life. As Caleb learns in the end, Sarah's love cannot be forced. Only by allowing Sarah her freedom can Papa assure her it is safe to stay here with him, hundreds of miles from the only home and family she has ever known.
Sarah's independence stretches back to her life in Maine. Clearly she learned her carpentry there, and, as the woman of the house, Sarah has been accustomed to the peer relationship she shares with her brother. They come from a loving family, and so Sarah is used to being treated like an equal in the household. Her willingness to give up this home and this independence for an uncertain future shows her bravery, as well as her love and respect for her brother. She leaves to allow him the happiness he seeks, and hopefully to find the same happiness for herself. These complex emotional issues are succinctly summed up by the author through the lesson that Caleb learns in the end. He had considered trying to prevent Sarah from leaving, but when she returns to him and announces her decision to join the family, Caleb's faith is rewarded. Sarah teaches him that he can trust her to be there for him, and that finding love is worth the scary risk of losing it.