What is the theme in A Solitary Blue by Cynthia Voigt?

Solitude is one of the most pervasive themes of the novel, even showing up in the title. Jeff's response to the way his mother hurts him is to draw inside himself to hide, and protect his fragile heart. After his night spent alone on the island in South Carolina, Jeff feels like he has locked up all his memories of that day and night in a "room inside himself" an