Quantum Theory of Undelivered Kisses

Given:
Evi, a math genius and owner of anxiety disorder;
Caleb, a future developer and Evi's best friend;
Leo, a newcomer and inventor of "adorable" solutions;
Milo, an unknown quantity.

Question.
What happens if in one equation are Evi, who has loved (unrequitedly?) her best friend Caleb since childhood, and Leo, whose grades have dropped because of how Evi bites her lip? And what if a third party appears—a mysterious pen pal? Life problems with a star, the complexities of communication with an overprotective mom, sessions with a therapist, first relationships and the difficult choice between friendship and love—why does everything happen like this and how to make sense of it all?

Solution.
See p. 320.