If Geoffrey still thought of Serena as just the attention-seeking lady he initially thought she was, then he could just go bang his head. He could no longer deny that he was wrong about Serena. She did not seek attention, but rather, she commanded it.
The first time, in the music class, he can still say that she did it on purpose. There was no need for her to volunteer to sing the song she composed herself, but she still did. At the wedding, he cannot say that she tried to win her way to the hearts of those elderly people because truthfully speaking, there was no benefit in doing that. The reason why she was the center of attention should be because she had the political backing and position to be catered to.