I think it is more like she took her hands off the wheel, remember a few chapters ago she was manipulating his fate to keep things ok, and he talked about a car accident on his normal route and such. So it seems since she isn't watching anymore cause she feels she doesn't need to is when this started happening.
I can't say I'm a fan of an enemy that can rewrite memory / reality. That's basically close to omnipotence, and any solution to it will naturally be contrived, or become a battle of gods.
If you dive into the broader When They Cry universe (including Umineko), the "world" is sometimes framed as a game board. In this meta-context, characters like Rika are "pieces on a game board" moved by higher-order beings (witches) like Frederica Bernkastel. From this perspective, the individual loops Rika goes through are indeed "tests" or "games" played out for the amusement or growth of these beings.
The "test" is less a simulation and more a meta-fictional game. To high-order beings like Eua (the secret main antagonist), the various loops are pieces of a story or moves in a game board. The 100-year struggle Rika (the secret main character) endured was a "logic error" on this game board. Once Rika finally "won" and discarded her human identity to become the Witch Bernkastel, she ascended to the same high-order realm as Eua/Featherine.
You're right though that in some way it will become a battle of the gods. So yes, there is a meta-character involved. The problem is reverse engineering:
who is in the fragments (game board world)
pieces only?
pieces and agents of the higher-order being?
pieces and the higher-order being itself? (ABSOLUTE WORSE CASE SCENARIO)
from the reader's perspective:
what is the fragment and what is the real world
what part of the story are you looking at
non-linear or linear plots?
loops?
Is there loop retention? Or is it a fresh start everytime?
In other words, character(s) are placed into a fragmented but real universe, unable to access the others. Taya and the others have to find the witch or "game-board" and break whoever is trapped out ("battle of the gods" route). Usually these fragmented worlds are incomplete and the chess pieces (in this case Haru) can break out on their own (naturally contrived route).
Or.... vice versa...
Haru was always from this world and experienced a fragment of living with Taya . It was all fake or forgotten, never to be experienced again.
Or....
Haru has been looping this whole time, finding Taya over and over again.
Or...
Everybody is real and have been whooshed into a fragment. Maybe some or all are even the same one.
I'm almost expecting him to wake up just to see whoever did this on the ground getting the McShit kicked out of them by his spider wife, her reaper father, and her human mom who would absolutely throw hands over this
vice versa...
