Why was he so mean to Chiles?

I never understood why Beau was so antagonistic to Chiles in the beginning. I know he dated her friend, however, they never mentioned any problems between the two of them. It seemed a bit out of character for him when he was making disparaging remarks on her song writing, stage fright, outfit, etc. Granted he did save her performance that night but I was not sure why he was so mean to her. Did I miss something?