Why am I so bored with working on my fictional projects, since I was and am so close to having a publishable product?

I have about 200 pages fleshed out for my graphic novel not even counting the art. I intend to hire a good artist or go in partnership with someone. I have like I don't know 20 brief chapters worth of writing, and I seem to be stalled out and running out of ideas to improve on the work and add to the work. It's a collection of chapters which are loosely chronological in which the four (or five) heroes battle increasingly powerful foes. I've been working on this damned project for over 3 years now, and seem to be stalled completely.

Why am I so bored with working on my fictional projects, since I was and am so close to having a publishable product?
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