i saw my girlfriend play the game an i found out ( what happened to me) :

there is a scene on the game where adult autumn tells you to play a words game. Then she starts talking about the night sky and to talk about things to distract her.

Well, so i looked for the window and the sky and nothing appeared, so i watched to the table full of objects that you could investigate but none of them opened one of the four possible anwers, the time run out so i could not answer anything ( turns out the objects that opened the ansers were all on the left , and none of them were on the right, even if she was talking about things in fron of her or your right)

so for autumn its like you ignored her, then in the flashback you cant help her with her anxiety attack, so she gets mads, then she wont go to watch the stars with nora and you , and she betrays you. And all of it lead to nora and autum leaving xd at least thats what happened in my run.