Ask HN: How to finish last 30% of a side project?

I'm building a small project for myself, a web page editor. There's a frontend framework, an editor, and a backend. The first few months of the project went great and I was a blitz of productivity. Now there's only a few features left I want to build, yet writing the tests for these and going back and forth on different decisions has killed all productivity and drive within me.

I have tests but changing existing behaviors feels exhausting. Even a small refactor, even with good tests in place, feels exhausting and I just don't want to pick this up anymore.

Part of it feels like I've tried to do too much at once instead of building piece by piece, but even building piece by piece doesn't work because at some point you realize a new feature requires you to revisit the architecture of a prior decision, and that just puts me off from ever picking it up again.

I'm tired, I'm exhausted, I want to finish, but this is a recurring problem for every project I start. It just feels like I'm unable to ever find a way to wrap things up and I'm always working in a spiraling circle instead of the meme about drawing a wolf with some circles, add some details, etc.

Is there a book or article one recommends? It feels like I never learned how to code properly, even though I've been coding professionally over 10 years.