The television
Early in the book, a television arrives in the plot as a symbol for entertainment and escapism. Once Gus has his beer and the TV, he doesn't care that none of the children are home, and he doesn't wonder where they are. He doesn't care about the family. He cares about television, comfort, and turning off his brain after very long, tiring, mentally fatiguing days.
Hatred as suggesting suicide
When the father tells the mother to go shoot herself in the head and die, that is a clear instance of hatred. The reader will notice that hatred is betrayal, because he hates his own wife and kids. The quality of his hatred is that he says things in a way that suggests she'd be better off dead. He betrays her by encouraging hopelessness in her mind. He is attempting to weaken her self-esteem.
Miranda the symbol
Miranda is the accidental child of a cheating mother and a cheating father, the daughter of an affair. Her life is a literal symbol to the family that the family is not a real family. If the mother can have other children with other men, then obviously the family trust has already fallen apart. Miranda's ironic life is also a symbol for hope, because out of the worse kinds of circumstances, Miranda is born.
The symbolic death
Rosie's death is an important symbol because it symbolizes that hatred confused her to the point of absolute despair and panic, and she took her own life by parking her car on railroad tracks. The death is gruesome, but it is also symbol. It symbolizes a mother's sacrifice for her family, because she lays her life down for the benefit of the family, but also, in this case, the death symbolizes the betrayal of the father, who encouraged her to hate herself. There is an important feminist argument to be made here.
The union around death
The death brings the family together, which is something that every family kind of understands in a way. Death does make family literally converge, because of the funeral. The unification of the family is also symbolic, because as the kids celebrate and mourn the life of Rosie, they also realize that they are not alone in their suffering, because everyone knows the truth about the family, having suffered together the whole time.
