Why did Claire treat dylan so badly?

All throughout the show, Claire kept pointing out how Hailey deserves better and used that to justify the mistreatment towards him. I never understood that, sure Hailey is really pretty, but she doesn't have any other qualities, she spent her highschool years partying and having fun, she got kicked out of college, barely ever had a real job, lived in her parent's basement. While Dylan has constantly tried to improve himself, move out of his mother's house, worked hard and got into nursing school.

If anything, Dylan is the one who deserves better. I love Claire and I understand her worry for her daughter but I really wish someone had given her a reality check.