What is the theme in A Feast for Crows by George R.R. Martin?

Betrayal is the driving force behind the actions of many of the less honorable characters in this story, as well as a few of the otherwise honorable ones. In A Feast for Crows, it would seem that everyone has at some point betrayed someone else, and in turn has been betrayed by someone else. Cersei feels that she has been abandoned and betrayed by almost all of her friends and ministers, when in fact it is she who betrays everyone who ever makes the mistake of trusting her.