tldnr: Christian is mad at Ana for making her own decisions like an adult.
Look this is the worst chapter in the whole thing. One could so, so easily skip it entirely and just go on to 11. 10 could just be a little parenthetical note: (Christian haz a mad.) And then that's it! No reason to go into details, really. In fact, the more detail, the worst. My draft of this chapter is better than EL's and mine takes way way less time to read so that's something.
Let's keep this brief, shall we?
But wait. Where were we?