LitCharts assigns a color and icon to each theme in The Sun is Also a Star, which you can use to track the themes throughout the work.
Immigration and the American Dream
Passion vs. Reason
Interconnectedness and Destiny
Isolation vs. Connection
Summary
Analysis
Natasha and Daniel sit outside. Finally, Natasha lets Daniel comfort her, and she says she needs to go home. Natasha thinks that it's possible to keep in contact, but they can't—their lives should be separate. She asks Daniel about his interview, and he answers unenthusiastically. Daniel says he's going to go to her apartment with her. He brushes off her concerns and insists that they're going to ignore that the situation is terrible. He's going to accompany her to the airport and then spend his life wondering what might have happened.
Natasha's insistence that they should live separate lives once she's in Jamaica again recalls the differences between the cosmic interconnectedness (which Natasha is now comfortable with having) and the intimate connection she and Daniel formed (which she wants to forego). Daniel's desire to wonder for the rest of his life suggests that he's not ready to let go; he still feels more connected than Natasha does.