As DanyiFri said there, Flynn wanted to know the truth about the death of his friend (and probably lover if they had grow up together?), he GAZED into the abyss and the abyss gazed back at him, his death is literally that. Now Flynn souls is stuck inside a time loop watching everything again and again, not only him, but all of the other's "people/monsters" before him, like a amalgamation of souls combined (But I hope he gets out somehow, maybe in arches since the title is "breaking the cycle" I haven't played arches, I'm waiting for it to be completed first.)
The good thing of a multiverse is that there's one timeline where he frees himself, one here he never became a monster, but those aren't """really""" inside the VN, the sad part of the multiverse, is that the Echo Dev's don't really want to make a real happy ending for a horror-terror story (I'm ok with that, terror/horror is about that..).
However, I would love to see something like "supernatural" series around Echo city, maybe a traveler fixing the stuff around the time lines, connecting all the stories somehow? Maybe Flynn and the monster would be the protagonists? I thought of doing that myself with different stories from other VNs, a traveler visiting the worlds and trying to fix stuff, but copyright is a thing I want to avoid for now, maybe a fan-story-tribute..
But that's it, he gazed into the abyss, the abyss gazed back, now he is stuck inside a time loop watching all the deaths again and again, lost technically inside the multiverse, at least a version of himself.