As much I'm happy she is moving on, this is something that kinda annoys me with other manga that do this, ie spirit reincarnated in body of another person and eventually that spirit leaves when they've achieved peace. Is that the body that they are occupying isn't just a shell, it's a person that the spirit has been squatting on for weeks, months, years. If it was like Yugi and the pharoah where they both are interacting with each other and both are conscience of one another. No, the true owner of the body is thrown into a literary coma. And when the spirit leaves they are like fully developed mentally, despite the fact the spirit has been occupying the majority of their developing lives, which makes no sense.
I dunno, there's a bit of an ethical dilemma/plot holes happening with this reincarnated cliche that just gets handwaved, which annoys me greatly.