Chris's relationship with his father is quite good at the beginning of the book. Upon graduation, Chris's parents throw a big party in honor of the accomplishment. Chris gives his father an expensive telescope and gives a nice speech of thanks and appreciation to his father.
Soon after, Chris leaves on a road trip which lasts until just about the beginning of the next semester. During this road trip Chris discovers that his father continued his relationship with his first wife (had a child with her too). He did this even while he was in love with his current wife Billie.
That discovery begins to change Chris's attitude toward his parents and even some of his friends. His attitude turns darker and he actively seeks time away from social interactions. That general attitude continues to build and Chris seeks opportunities to stay away from his family during breaks/vacations. He goes on more road trips, lives by himself, and has few belongings. As his resentment of his parents grows, his resentment of just about everything else grows with it, so Chris wants to more or less leave all of it behind and be in solitude.