This dude right here is a fucking genius. About the "Happy ending" thing i though on something like that: You find all the hints, and do some specific things, then you get the key to the exit, you go to the exit but just stop there, without leaving, and then you turn around and she is standing right there, you keep still, then she approaches and hug you. And then she say something like "Now we can stay together forever" and you hear the keys drop in the floor, and the "Happy Ending" Appears. It would br like a dream for me~
In this scenario with how she is. I don't think a love ending would be possible. She already has blood on her hands and quite unstable. A real life case actually happened awhile back where she literally killed her lover and wrote in his blood about how much she loved him. There's a photo of her smiling in the backseat of a police car and it got a bit attention because a bunch of degenerate weebs went out saying "I'd smash, I'd love her, she'd be a great gf" when irl. You really be saying otherwise when she's cutting you up for talking to a girl even though that person was your mother.
However it is a game and it would be great if you could help her break free of the attachment (as in being overly attached) and then having to dump the body or frame someone in order for it to be possible. I think they might be sticking to horror though as a genre, or finish the horror aspects of the game. But at least this game has a happy ending that you earn.