After losing her husband in 9/11, Twin Towers, one of the mothers in the story suffers from chronic depression, and the daughter basically becomes the 'carer' for a while. (Near the end of the book the mum eventually comes out of her depression.)
There is mention of suicide: WWII German Jews secreting cyanide tablets away to be 'used' if needed. Before Hannah's family 'left' Germany her mother was definitely suicidal; hence Hannah wondering if she would have to kill her parents as they didn't seem 'brave' enough to do it.
The author shines the spotlight on a 13-year-old girl receiving her first kiss, and how important it was.
Understandably, due to the era, topics, and, setting of this book, Correa seems to focus on death, and, the characters in this book being able to choose the time when they want to die - by just giving up the will to live - which is how the book ends.