I'm not even sure if I really like American Horror Story, but I do know that I preferred Evan Peters best when he was Tate and less beefy and more '90s, blowing away teens in a library. Now he's a drunken freakshow attraction with dirty lobster claws for hands. I would say that excessive drinking was 85% responsible for his hurling in this scene, but I think we're also meant to believe that he was having realization and repulsion over humping (and feeder fetishing) the fat lady, which is kind of uncool. This is the second example of fat sex with a disposable character=hitting rock bottom for a male protagonist.
I won't say why Skylar is barfing in the Gracepoint finale in case you haven't watched this show and want to. But despite what was promised, the story hews very close to Broadchurch so if you've seen that you know the answer.