The Missing Pieces

Common questions that people may have include: Where did I come from? Why am I here? Where am I going after I die?
Mateo Rivas tends to overthink, which has caused him to lose interest in things. During his older sister's wedding, Mateo meets Charlotte Robertson while trying to avoid socializing with his family. Their brief conversation sticks with Mateo, and he can't seem to get her out of his head.
After winter break ends, Mateo sees Charlotte at school and wants to talk to her. To his surprise, she's the one who starts the conversation. What does she want? Why is he so interested in this girl he just met? How will Kairi, Mateo's girlfriend, react when she sees Mateo with another girl?