I am going to go out on a limb and say
What you are going through is a normal thing we go through as humans when we separate from another person and are not the one making that decision.
Your brain tricks you into wanting someone MORE when you feel rejected. It's an ego survival thing.
You want their validation. You want them to confirm that you’re not disposable. You’re not worthy of rejection. And so, to prove it, you want back the person who implied that you were.
You’re not worthy of rejection. Here’s why.
One person saying this isn’t for me isn’t a declaration of the entire world saying you’re bad or something’s wrong with you. It’s one person.
When the feeling is that someone rejected you, usually, if you’re really honest with yourself, you weren’t content in that situation anyway.
When someone rejects you, the ego steps in and demands they take it back. You don’t want to feel like you are dismissible. You want to feel essential, especially if that someone felt essential to you. The feeling of rejection can break your heart and make you question your worth all at the same time.
When you feel a pull to the person who rejected you, realize what you’re wanting is not that person. It’s reassurance that you’re worthy of acceptance. It’s the apologetic expression of the rejecter that they made a mistake and should never have let you walk out of their lives. It’s bandage for a wound. It’s healing to make you feel whole again.
But they don’t have that thing you need. It’s not with them, it's inside you.
Oftentimes, people simply don’t match up. You may have compatible pieces with someone but not a compatible whole.
After some time, this trick in your brain, this love drug withdrawal you are feeling, is going to end.
On a personal note, it will feel a lot better when you make the decision that they really are not good for your future and you leave them. Even if it's just in your heart and she doesn't know it. It starts to counteract the ego's need for validation.