Spoilers:
It's almost lie they're both yanderes, because it plays the soul mate/ fate bound card so hard.
I actually liked the ending where she bit him to turn herself, but that's short term satisfaction. What's to keep them from literally going insane 100 cycles more? And I was actually a bit sad on the ending where he turned to ash. If it'd been elaborated on more, I might have even teared up. It was giving me "interview with a vampire" flashbacks for sure. The "Let's Fight Fate" haha I wasn't feeling optimistic they'd succeed. But I love the kinda fourth wall breaking meta memory thing. Thanks for making it, I'll put it on my recommend list.