I guess it’s up to the hurt party to decide if the person who hurt them is genuine and worth it. But that person should understand that they’re not owed a second chance because they’ve changed. If someone gives them a second chance then that’s far more than they deserve.
Some people assume that because you gave them the space to get their shit together, they can breeze back into your life without doing some serious work to regain your trust. The trust isn’t automatically there because of your history etc.