Solve this puzzle for me!

Ok, I'm super struggling with plot for my story and need some fresh eyes/ideas. No storytelling/writing skills needed. You've read books. You've seen movies. You can totally help.

This is what my story looks like. Oy vey.

Here's the premise (it's a Young Adult Fantasy story):

Ilan is a land with no future. The Relater, the only person who can write storylines to keep the world from crumbling, has been lost. Ilan depends on the dedication of Seekers, who steal pieces of others' futures, and heralds who open portals to the other worlds who have storylines to spare. But it's only a matter of time until the Seekers cannot supply enough futures and thousands will perish. 

The Relater must be found. Elsi, Ilan's best herald, must aid two Seekers in their mission: find the Relator, and don't come back without him.


Make sense? The Relater is a god-figure basically. He creates life by writing your story (imagine your story is a book and so is mine, all kept in a library. No Relater = no stories = no life = bad)

So far so good?

Ok, my character arcs (what happens to them and how they change) are fine but my plot is falling apart. The main goal in the book is to find the Relater. At some point the group discovers that he didn't get taken as they had believed, and as their government kinda told them, but that he left on purpose. They end up finding him in the end, but my quandary is this: why did he leave? I need there to be a reason, and a good one (since him going missing is the whole premise this book is based on).

Right now, I have it that he left because people (mostly in the government) sought the Relater to abuse his power so he (and his siblings-that's another surprise) have been hidden away in other worlds until their world could be purged of corruption.

Dear stars, that's so cliche. And seems, meh. This is the backbone of the story and while again, my character arcs are good (hopefully) I don't want people to get to the end, see this, and think "what the heck?"

I feel the reason why he/they left needs to be better (and there can be just one Relater-I'm fine with that). He is the creator of life in their world, and their world will cease to exist without him. He left voluntarily. Why??

This I do not know. Sigh....any ideas??