To begin with basic fact, people are confusing with their lives and thoughts that are so intricate, individual, and beyond understanding. Why they do things can't be explain with a couple of sentences and words mashed together.
Nicki Kowalski, a boy living in a small town with family falling apart, superficial friends, and his last yeat of high school staring him in the face, has very little he gets worked up about anymore.
Francine Spencer, a girl who moves to previously mentioned small town and sees the light in everyone, believes in the adventures that lurk in the night, and and can carry a decent and deep conversation, enjoys the company of the melancholy boy.
Out of everyone Nicki can deal with, she's the one he can't wrap his head around and the one he can only try to explain her and the entirety of the months they share together.