Grief (novel)
During the course of the novel, the ideas of the stages of grief are introduced. The stages are denial, anger, depression, and acceptance. The narrator, as well as other characters in the story, slowly passes through these stages in trying to deal with death.
Prolonged grief disorder
PGD is defined by its symptoms, duration and intensity. The symptoms are intense yearning for the person, identity confusion, difficulty accepting the loss, bitterness, emotional numbness, inability to trust others and the feeling of being trapped in grief. These are present every day, causing significant distress and functional impairment, and remaining intense, frequent, and disabling for six months or more after the death.