Relationships
Relationships are a key theme of many of these short stories. This could be general relationships with friends and family or romantic relationships. Often, the protagonists of these stories struggle with their connection with others, whether it's due to their own feelings of inadequacy or their feelings of alienation.
Loss and grief
Loss and grief are present in many of the stories. Many of the protagonists are dealing with death in their lives, often due to illness. For example, the narrator of "Breathe," lost her younger sister to cancer, and in "Cancer Poems," the protagonist is dealing with her own terminal illness. In "Another breakup song," the protagonist deals with another sense of loss, due to the failure of a romantic relationship.
Unhealthy habits
In "Breathe," the narrator has a few unhealthy habits, including binge eating and watching a lot of TV. Ultimately, these habits are actually an externalization of her unhealthy inner life. She hasn't dealt with the problems in her past and uses these habits as a way to distance herself from her own problems.
Identity
The protagonists in these stories are often dealing with conflict within their own identity, due to repressed problems or an inability to deal with their own flaws. In "Breathe," for example, the narrator seems to blame her problems on other people and sees the world in a cynical way as a result of this. In "Another Breakup Song," the protagonist must learn to find herself again after the breakdown of a relationship.