One day, Juliet, Remy, and Dawsey walk to St. Peter's Port for supplies. They pass a large dog, tall and seemingly harmless, but Remy quickly begins to vomit and convulse uncontrollably upon direct sight of it. They carry her back to Juliet's house to recover. Dawsey later comments that Remy has flashbacks of the dogs that used to guard her cell block at Ravensbruck concentration camp. Juliet relays this story to Sidney with sympathy for Remy, but still contemplates at the letter's end whether Dawsey might have feelings for Remy.
A few days later, Sidney writes to Juliet to announce his second visit to Guernsey to see both the islanders and the Oscar Wilde letters. He also points out what he believes to be quite obvious: Juliet has undoubtedly fallen in love with Dawsey. Juliet grudgingly agrees with his observation. Isola also responds to the news of Sidney's impending arrival with an invitation to Eben's upcoming beach party and the message that Eben will be making a very special announcement.
Meanwhile, Juliet makes a formal announcement to Amelia of her plans to adopt Kit. Amelia wholeheartedly agrees, and the two women cry with joy about the happy new development. The following morning, Kit wakes up Juliet with her small box of hidden treasures in hand. To Juliet's delight, Kit finally reveals each of her most prized possessions: several of Elizabeth's small trinkets, a photo of Elizabeth smiling up at Dawsey, and a small leather book of poetry from Christian to Elizabeth. Also included are the World War II medal that belonged to Kit's grandfather and the magic badge that Elizabeth had pinned on Eli when he was being evacuated to England. Juliet is speechless at Kit's display of affection, sure more than ever that she wants to become Kit's mother.
Beyond her relationship with Kit, Juliet now speaks openly of her feelings for Dawsey in her letters to Sidney. Even seeing Dawsey with Remy ignites jealously, and she blames Sidney for making her admit such foolish feelings for Dawsey at all.
The novel then features "The Detection Notes of Miss Isola Pribby," in which Isola spies and records the doings of the islanders. On Friday of the first week of Isola's observations, she records the arrival of Sidney — noticing with a superior eye that Juliet and Sidney embrace like no more than siblings. On Saturday, Isola records Eben's beach party, noting the Dawsey does not warm to Sidney. She wonders why this might be. That evening at the bonfire, Eben announces that Remy will be moving to Paris to apprentice for a famous confectioner, a lifelong dream. Isola then comes to a conclusion — based solely off of her spying skills — that Dawsey is in love with Remy and is devastated that she will be leaving. She decides she must find evidence of Dawsey's feelings and prevent Remy's departure. To do so, Isola hatches a plan to snoop around Dawsey's home for evidence. Unfortunately for her original theory, Isola only find evidence of Juliet in Dawsey's home — a small handkerchief with a J embroidered on it, and several photographs of Juliet and Kit. Utterly defeated, Isola runs to Juliet to cry about her failed mission. Juliet, on the other hand, does not believe the mission to be a failure at all. She quickly runs out the door to find Dawsey, now on a mission of her own. Juliet finds Dawsey atop a ladder and proposes marriage to him on the spot. Dawsey, so ecstatic that he practically falls off the ladder, happily accepts Juliet's offer. Nine months after their first correspondence, Juliet and Dawsey will finally be united as husband and wife.
The impossibility of completely forgetting the horrors of war, an ongoing theme throughout the novel, is again exemplified by Remy's vomiting episode after seeing the large dog on the road. Dawsey's quick observation that the dog reminds Remy of the guard dogs at the horrific Ravensbruck concentration camp serves as a reminder that her healing process is far from over. A mere glimpse of a dog unleashes a flood of terrifying memories for the fragile Remy. The incident marks Remy's first and most vocal display of mental instability brought about by her experience — she has been relatively quiet since her arrival. The episode also highlights the sad reality that no one, no matter how caring and attentive, can completely erase the emotional damage experienced by a victim of war. Dawsey laments to Juliet that he had been ignorant to think that his goodwill alone could help Remy forget what she had been through. Juliet and Dawsey learn firsthand that hardly anything can be done to ease the psychological repercussions of war.
Juliet, on the other hand, has reached a state of phenomenal mental clarity for the first time. She has undergone a drastic transition since the beginning of the novel, now fully aware of what would make her happy. She is confident enough to finally make life-altering decisions to attain these goals. While on Guernsey, Juliet has learned invaluable information about the German occupation, but she has learned even more about herself and what the future holds. The legacy of Elizabeth McKenna — her life story, the daughter she left behind, the strength of her spirit — has functioned as Juliet's main inspiration throughout the novel. Juliet is prepared to be a mother to Kit, spend her days with Dawsey, and love the islanders like family. Juliet embraces that she will live a simple life, but one infinitely rich in love. She can finally fill the voids that Elizabeth McKenna had left behind.
Juliet takes several monumental steps to fill these voids. First, she officially declares her intention to legally adopt Kit. Juliet and Kit have hit an emotional pinnacle of their continually developing relationship and long to live together as mother and daughter forever. This realization is most evident when Kit chooses to reveal the contents of her secret box to Juliet. All of Kit's most prized possessions pertain to her late parents, Elizabeth and Christian, or to her loved ones on the island. The gesture is essentially an invitation for Juliet to stay in her life forever and to know her deepest secrets.
Juliet is now self-aware enough to admit for the first time that she has no interest in moving back to London. She cannot imagine a life without the beautiful island, her new friends who have become family, and a familiar atmosphere in which to raise Kit. Furthermore, as Sidney has to point out, she is madly in love with Dawsey. Isola's humorous detection notes provide an objective account of Juliet and Dawsey's long-awaited romantic union. Juliet's proposal to Dawsey is the final step in her journey toward self-fulfillment — her ultimate act of bravery and a single action that propels her toward a happy future.