Serena was annoyed. Fine, they broke up, but it has been over week! How come he never took the initiative to contact her? It's not like he didn't know where she was. He can even send a card as he knew her parents! Not even a simple congratulatory remark for the success of their song? If she knew how or had ways to contact him, she would have already.
The only person who can send her message to him was Leonard, but she was too ashamed to ask for his help when he clearly told her to at least try things with Geoffrey.
