When the girlfriend is dead, but before she died, she wrote letters to the boy. Nurse gives the boy a box with a note that says, "Read for when the time is right." And each letter has a scenario that the boy might go through. (Ex: For when you miss me, for when you fall in love, for when you're angry, etc.) They are young adults so the boy reads the letters until he's old (letter that says, "For when you're about to die." And it says something like, "See you soon." At the end.) I'll make an edit sometime today or this week if I can.