He frown crosses his features as she moves away from him. He feels like an ass for being so selfish and tied up in his own stuff that he hadn't noticed before now that something was bothering her.
"But something happened." he repeats, still frowning. "Lydia...was it Stiles?" Because something about bow closed off she seems right now just makes him think he must have been him. And some part of him is already angry on her behalf, whatever he'd done, whatever he'd said to upset her like this...he'd lost that right a long time ago.