The ending. Good God. Eleanor gets away from Richie, but she and Park are separated for God knows how long.
All the scenes describing Eleanor's home life.
Eleanor's biological father clearly doesn't give a damn about her, and Eleanor resorts to stealing things from him such as soap and toothbrushes to bring to her mother and siblings. Her stepmother catches her, but doesn't say a word.
Just Eleanor's relationship with her father in general. When he calls her, her narration points out that he hasn't contacted her for at least a year. And it's only to get her to babysit her stepbrother. When they are together, they barely speak to each other, and it's obvious that he barely cares about her or her brothers and sister.
When Eleanor is staying at Park's house, she takes note of all the "little luxuries" he has. They include canned soup, soda, brand name cereal, newspapers and magazines, and soap and toothbrushes. It really shows how poor she really is when she considers a toothbrush to be a luxury item.
Eleanor's mother's attitude toward her children. Although Richie constantly abuses her verbally and physically, she still defends him at times.
