Rowena falls on a Sunday, when Stuart is supposed to be watching her. Robert, however, blames himself because he was his sister’s “guardian” yet was masturbating in his bedroom when he feels he should have been there to save her.
Although Rowena’s death is an accident, Robert blames himself. Having always felt a duty to protect his sister, he has lost his sense of purpose. The trauma of Rowena’s death marks a symbolic end to Robert’s childhood, as he is now forced to grow up and find meaning elsewhere. It’s also notable that when she died he was masturbating—that is, exploring his own sexuality as part of coming of age—which adds further complexity and trauma to his process of growing up.