The thing is that...I have a lot of empathy for Air...But she doesn't understand that Pure won't save her. Her relationship with Pure won't save her. I would even say it'd make it worse.
What she needs is not a relationship to cling to. What she needs is freedom. And even if being with Pure used to be freedom and happiness, it's not anymore, because too many things have been broken.
She thinks that if they get back together, she's going to find again this sense of freedom and personhood she used to feel when they were together, but time has passed and neither of them are really the same person. What she needs to do isn't standing up to her mother to be with Pure, she needs to stand up to her mother FOR HERSELF, and herself alone.
Once she has truly gained back this agency and embraced who she is as an individual, then she can go back to a relationship.
I don't blame her, she's looking for safety. But in doing so, she's hurting Pure and stopping her from moving on. She keeps Pure believing that she's the one who'll save her, and that she needs her, and Pure stays because it'd feel like a betrayal if she didn't, it'd be like abandonning Air to her fate, without giving her the support (and an argument) to stand up to her mother.
But at the end of the day, it's just going to hurt them both, and send them back in a place where they don't belong anymore and where they'll feel uncomfortable, out of themselves.
It's just like Bam pointed out : it's been broken...And it'll never be the same again...it doesn't fit back together...You'll always see the cracks it left
