Despite her fear that she'll hurt Augustus when she dies, Hazel finally lets herself fall completely in love with him. Until now, Hazel has been reluctant to let down her defenses and allow herself to feel the strong emotions she obviously has for him. In this section her defenses give way, and Hazel admits that she's fallen in love with Augustus, comparing it to sleep, which starts slowly and then comes all at once. Her change of heart, though it was probably inevitable, comes just after Augustus comforts her over her sadness about the swing set in her backyard. Hazel worries a great deal about the suffering she inflicts on others, and the incident occurs just after she's been reminded of the pain her cancer causes her parents. Augustus helps her temporarily forget about these worries, and as a result she seems to worry less about the pain she may one day cause him as well, focusing instead on letting herself enjoy the present. It's a big step for Hazel emotionally, and it allows her to feel even closer to Augustus.