edit: deleted my original comment but wanted to keep in that I love this so much and it's so well-made and well-written and everything <3
ok I found out my problem!
so the walkthrough wasn't accurate for me: I got the bad ending just by not having enough affection. With that, Goro declines coming inside to talk to you and you automatically get the bad end. When I DID level up his affection all the way, I tried choosing the options you listed for the bad end ("no, it's nothing" etc. etc.) but I still got the good ending.
Wanted to let you know in case you decide to edit the walkthrough!