Here's - Nr. 2.
The dev does update on itch, once the update is ready.
Read the Ch5 DevLog here:
"For those of you who prefer getting it here on Itch, Chapter 5 will be released the moment it's out of early-access/is a finished build."
Production has a lot of factors, so far every update had new locations, the writing is phenomenal, especially considering the path approaches for each character. That takes not only a lot of subtle writing, but also a lot of planning, and as paths diverge will take even longer than it currently does.
To paraphrase a german proverb: "Good things take their time."
Look at Projects such as Ripples, or what NiiChan and Caribdis are pushing out.
Eternum's last update took more than 6 months.
If u don't wanna wait that long that's fine, be angry about it. But don't throw a public hissyfit, tryna discourage sales. Jerk off, and let the anger subside.