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
As Daniel races out of the Fifty-Second Street subway, he almost runs into a couple, both with blue hair, kissing furiously. People gawk at the couple and some make disapproving noises, but the couple makes Daniel extremely happy. He hopes their relationship lasts forever.
The couple is clearly the same one that Natasha saw, which allows the reader to recognize that even though Natasha and Daniel are far apart right now, their experiences still connect and inform each other.