Guess who killed I Ren it's himself from a happier timeline and I have something in the lore that said.
If the person from another timeline killed the original version of a difference timeline, time would shattered and reset to the moment before it happens but since it didn't happen it happen again, run on a loop until it's all go that it and reset to a completely new timeline and history to completely prevent that very thing to happen but when it's completely prevented to happen that thing earlier would not happen and it happen again.
Yes I love saying nonsense because I'm bored