Arthur sighs and shakes his head again. She must realize that Eames tells him things, that they talk and have gone past the point of keeping big secrets from each other. Maybe she's withdrawn so much that she doesn't even know how involved they've become, but that's her own fault, and Arthur's not about to volunteer up information about his personal life for her benefit since she's the one that wanted out of everyone else's lives to begin with.

Whatever she knows or doesn't know or realizes about what Arthur must think he feels too upset to keep trying to tell her that she shouldn't be stealing to scrape rent together. He's just so disappointed.