It's not like there's anything else going on,
Let's invent a story!
Rita is writing a Harry Potter - Severus Snape fan fic. Nora has some issues with a minor plot point, and that's what the fight was about.
Looks like Rita is trying to get some work done, and Nora's tv watching is disturbing her.
Rita pointed upstairs, as if Nora should go up to watch her movie.