She knows that it’s attachment that makes her go after people who aren’t meant for her. She knows that it’s attachment that compromises her logic and her reason; it’s what dulls her senses. She knows that attachment only feeds into her fears and insecurities; and it doesn’t make her a better person overall.
She doesn’t allow herself to get attached anymore because she now knows that not all things in life are meant to be; not all things in life are meant to stay forever. She has finally grown to understand that just because someone walks into her life doesn’t mean that she gets to keep that person for all of eternity.