Percy blurts out the truth to Sam immediately after they have sex: she slept with Charlie. While Percy cries, apologizes, and tries to explain that she felt abandoned after Sam left and after his letter made her think he was done with her, Sam initially says almost nothing. Percy also admits that shame and self-loathing helped drive her to destroy their relationship, and she begs Sam to tell her how to fix any of it.

Sam finally reacts, but not gently. He asks Percy how sex with Charlie was, shocking her with a cruelty she has never seen from him, and Percy hurriedly gets dressed and tries to leave. When Sam accuses Percy of running away again, the argument shifts from the confession itself to what happened after their breakup: Percy says she believed Sam hated her and had nothing left to return to after the cottage was sold, while Sam says he was still there every summer and holiday, waiting.

As the fight escalates, Sam shouts that Percy slept with his brother. That phrasing makes Percy realize something she had not understood before: Sam's silence was not simply because she rejected his proposal; he already knew about Charlie. The revelation scrambles Percy's sense of the past, and overwhelmed by panic, she bolts from the house, runs toward what used to be her family's cottage, and breaks down when she sees how much it has changed.

Sam follows Percy and finds her in the middle of another panic attack. His anger gives way to concern as he helps regulate her breathing the same way he did earlier, guiding her until she can slow down. Once Percy can speak, she forces herself to say the real horror of the moment: Sam already knew. Sam confirms it, and Percy collapses under the weight of that truth before blacking out in his arms.