Alice goes to the tree house expecting to find Charlie with friends, but instead discovers him alone and withdrawn. After she asks if he is okay, Charlie bluntly admits he slept with Percy. When Alice asks when, he explains it happened a long time ago, the summer before Percy and Sam started university, when he was twenty and Percy and Sam were in a bad place.

Charlie says Sam had pushed Percy away and was hanging out with other girls, leaving Percy uncertain about their relationship status. He explains he thought Sam was being ungrateful and admits he might have been in love with Percy, or at least jealous and lonely, wanting what Percy and Sam had. He describes the aftermath: Percy and Sam did not speak for over a decade, Percy punished herself, Sam hated Charlie and closed up like after their father died, and their mother was deeply disappointed. Charlie calls it the worst time of his life aside from losing his parents, while acknowledging it was worse for Percy and Sam.

When Alice asks why he is telling her, Charlie says he wants her to know what being friends with him entails. Alice weighs her shock and jealousy but chooses not to attack him. She tells him he was twenty and made a bad decision, but not alone in fault. She points out that Percy and Sam have reconciled, married, and are expecting a baby, and asserts that the man Charlie is now is not defined by that past mistake.

Charlie insists that is who he is—the man who slept with his brother’s true love—but Alice counters by listing evidence of his current character: building the tree house for his future niece or nephew, baking her birthday cake, taking Nan to choir, and being kind and considerate. She emphasizes she is friends with him now, not his past self, and that she likes the man he is, even if he is high-maintenance.

Charlie confesses he is still selfish and wants things he shouldn’t, then his attention turns to Alice. After a charged pause, he kisses her. Their encounter escalates quickly and passionately as they undress and exchange intimate words, with Charlie alternating between hunger and tenderness, telling Alice she is incredible while they hold hands and kiss slowly.

The moment is abruptly interrupted when the door opens and Sam walks in, exclaiming in dismay. Alice and Charlie jolt apart, Alice clutching her jumpsuit closed, while Sam looks at the ceiling and sighs that he should have known better, catching them in the act.