"Maybe the way the game ends him being dead is him being killed off finally for the false accusation. The girl in the third and fourth ending might involve something with Soutarou." I already mentioned it, sadly, I can't seem to think of anything now. The only think I could think of now is the girl. (Third and Ending with no number.)
The girl kind of looks of the girl that teleports you to somewhere you get the Pair of Hands. (The one in the sailor seifuku/uniform.) It's possible she was friends or something with Soutarou. I wanted to play with the effects so I equipped the Picture Frame and broke it. The girl's face became bloodied including her eyes or her eyes turned red. It's possible after the accusation she immediately hated him for doing such a thing.
And she possibly searched for him and wanted to kill him... (As time passed, I think I'm getting way more theories...)