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
When Irene takes her lunch break, she downloads the Nirvana album Nevermind and listens to it three times through. Like Natasha, she hears Kurt Cobain voice her own misery, but she lets his words take her to a very dark place. She looks Cobain up online and discovers that he committed suicide, and she decides to commit suicide as well. She writes her suicide note: "Oh well. Whatever. Nevermind."
Irene's suicide note takes a line from the Nirvana song "Smells Like Teen Spirit." Her decision to commit suicide after learning about Cobain's suicide shows that not all connections are positive; some, when combined with one's own isolation, can be deadly.