Something tells York that South is protesting too much. That she's saying these things because she wants them to be true, rather than actually being okay on her own, or preferring it. And he doesn't want to take her brother away.

"I didn't say you were a kid. Everybody needs company." He thinks for a moment. "Since we're not at each other's throats anymore, I could crash there sometimes. Call it a sleepover if anybody asks."