What is the theme in What's Eating Gilbert Grape? by Peter Hedges?

One of the primary themes that runs throughout the novel is relationships. The novel reveals that even the individuals that make up a family have different relationships among the family members. For example, Gilbert and Amy work well together as a team in taking care of Arnie, Ellen and Momma. Janice and Larry, on the other hand, are rather detached from the family and only send money and showing up once or twice a year to visit.