1) A final, proper good end, something where Vance and the player character get to spend some time together without the threat of... Violence. Just something so they both see each other again. Yandere is fine, but I do want that happy ending for the guy.
2) As said below, Vance's sudden violent shift isn't really explained that well. It could do with a few extra text boxes padding it out, making it a slightly more gradual thing.
3) Having nightmares locked behind tea, or endings locked behind candy - it can work in theory, but in practice I was just spamming different choices trying to find secrets. I don't think having so many options that are ultimately meaningless is a good fit for this story.
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While I'm flattered to see you empathize with the characters and hope this doesn't come off as rude, if you're looking for a real, pure, fluffy good ending, you're playing the wrong game.
Hopefully the game's description wasn't misleading - TSOSA may not be particularly extreme or conventional horror, but it is still horror. Harm is at the core of the story and at the core of Vance's presence. This will never end well.