He can't help that his eyes roll back in his head. It's just frustration, and he's not venting it at her so it has to come out somewhere else.

"I keep telling you. It's this funny thing, maybe you've heard of it, where if you spend enough time with someone in their good company, you become friends. And then when you find out that your friend has some pretty big troubles in their life, you want to help them out with them. Am I speaking English? Or do you just not believe me?"