When the game forcibly brings the players straight back to the menu, the result is Sayori being switched with a scrambled up mess of each of the other character's sprites where she used to be. The protagonist thinks to himself that this is his fault, that she is gone forever and that choosing the other option when hearing Sayori's confession would have prevented this. When the protagonist enters her room, the game will start glitching out and the music will heavily be distorted, playing the song ' Sayo-nara', a distorted version of the game's menu theme. Regardless of the protagonist's choices related to Sayori or not, earlier in the game, what the player sees will be the same: Sayori will be hanging by a noose from her neck upon entry. Sayori's ending happens at the end of Act 1. (Note: This isn't necessarily an ending to the game, but more the events that lead to the end of her life.
Character-Specific Endings Sayori's Ending