Here's my theory for that memory sequence: It was his memories of the past life where Ivona died, and he just got them back! I mean like, he says "Dead, in the end..." and talks about "Saving the world, but he couldn't protect the one he wanted to the most." But he hasn't saved the world in his backstory prior to the Demon King popping up! We know Ivona had befriended him in that life, and that he'd protected her back then, too... I think he's the reason time got reversed! He just didn't remember... until now. I wonder what he did to reverse time...