Ron had been waiting in his room, not at all patiently. Hermione storming out had been his fault, even if he wasn't sure how. And he'd been helpless to do anything about it. It was not a feeling he appreciated, at all.
So he was relieved to see her enter, even more so when she sat down beside his bed. And then answered her question honestly. "Awful. Shouldn't have tried to follow you."