Leila has enough going on with being an Iranian doctor's daughter who has no desire to be a doctor and isn't a particularly high achiever in school and has an older sister doing pre-med at Harvard, plus she has only two friends, neither of whom she trusts with the issue larger to her than her family concerns. Leila is a lesbian and is terrified her old world parents will disown her when they find out. Since Leila hasn't had anything romantic in her life except one girl at a summer camp, she hasn't had to actively hide her identity from her family or classmates. That changes when wild and sexy Saskia blows into town from Switzerland and takes an interest in Leila. Leila is instantly smitten.
Though Leila's discomfort one can see how loaded sexuality can be for a teen, even in today's climate, which feels more open, especially among millennials and the group behind them that is yet to be named/pigeonholed. In the opening scene, Leila's English class is discussing Celie and Shug's relationship in The Color Purple. Leila is squirming with discomfort at the idea of her classmates discussing lesbian sexuality. At the same time, she makes an assumption that everyone else is straight.
They're the girls every guy at our school has fantasized about since we were in ninth grade, which I find strangely disturbing.
Every guy? Really, Leila? But that's an expression of her isolation, that she doesn't think about anyone else being gay (she refers to herself as gay or lesbian throughout the book. Have you noticed that mainstream YA is slow to adopt "queer"?), except for later on when she makes assumptions about a trio of lady theater techies--and mocks their vegan diets. I don't know if that's intentional, but I think it is. Leila is judgmental herself, which may be why her fear of being outed is so heightened.
I'll stop now so I don't spoil anything for you.