While it's interesting viewpoint I'm leaning more toward Bella's mental problems and her seeing James next to her to be exact. As there was a theory that library scene from Bella's past was actually just Bella talking with her imagination (and James is long gone and this point), it does connect with some other points in the story. The scene with MC and Bella in a library and "call for help" is one thing, closed closet is another (maybe in Bella's mind James is phisically present there), and also during the date at Luigi's when Bella goes to the toilet she says to the mirror:
View attachment 1825036
Which obviously is adressed at James, but maybe it's on deeper level, not meaning that James is not present in her life anymore, but that he's not at her side at the moment (could be because of Bella's choice to remove the ring, James stopped appearing next to Bella).
That would mean Bella's fully aware of her mental state and she knows that James is not real (contrary to the flashback library scene), and it would also explain her reluctance regarding removing the ring - she's still torn between her old life and moving forward, and removing the ring could be a symbolic gesture of accepting that James is only a creation of her imagination and letting him go.
Ofc in reality it'll probably end with only a mild drama titled "I can't get over my long gone husband, but with power of your dick I'll overcome my trauma", but since we'll get to this point in a few years there's still time for some crazy theories