I recently finished the update, and I don't know what you all mean about the quality going downhill. The renders and dialog are just as good as always, IMHO. Sure, it's not that lengthy, but whatever the dev can do in a reasonable time, I'm thankful for.
I am sorry to hear that the dev is so stressed about Hillside and unhappy to work on it. Honestly, life is to short to devote time to things you hate, so if the dev really hates working on Hillside, than he should just stop. We will all be disappointed not to see the relationship between the MC progress further, and see the story play out, but there are many other games.
I really think the main issue, is that the story has grown more and more complex, and the dev isn't sure how to wrap things up. If I were the dev, I would take a break, and then when you want to work on it again, write out the whole story, from now until the end, decide what part of the story goes in each update, write the dialog, or at least an outline, before doing anything else. I think the uncertainty and stress about where the story is going, and how to end it satisfactorily, is causing most of the issue with development, I could be wrong of course.
I hope, DarkBlue, if you see this, just take a break for however long you need. 3 months, 6 months, whatever. If you don't feel a desire to go back to Hillside, and enjoy working on it, and seeing the story move onward towards completion, don't do it. Find something else to do with your time that you enjoy. Watch Netflix, take a walk in the wilderness, join a club, whatever you enjoy doing.
We all would love to see it continue, but if dev says they dislike working on their game, really, it's time to take a long, long, break until they feel differently, or just hang in the towel.