Theory: Carmy had an affair with the abusive head chef in New York (played by Joel McHale)
I haven't seen very many people share my theory that Carmy is queer but I just did a rewatch and I'm even more convinced.
He told sugar his problems sleeping started in New York along with the throwing up
In the dream montage in episode 2 there's a voice over of the head chef being abusive and the ticker is printing out what the head chef is saying UNTIL it prints out two things that weren't said: "He didn't love you" and "You killed Michael" (see pic)
The "he" in question could be Michael but based on the flashback scene I feel like Carmy knew his brother loved him
There's also just the way he reacts to Richie's homophobia and at the Al-Anon meeting he specifically says he "didn't have any girlfriends"
In conclusion, queer!Carmy season 2 thank you very much