The two go back to the school ultimately to not just save their friends, but to put a stop to the overall curse. Hell, that was the point of the two groups disagreement that last chapter. You find out you pretty much HAVE to stop it, so you do, only to find out that there's really no stopping this train. Sure, you're able to get off(4 people lighter than you got on), and so long as you forget that the four friends that did die will suffer for ALL ETERNITY in that hell, be happy you lived!
I don't mind a game that pulls the rug out from under the player, especially done repeatedly, but not at the resolution of the game, cause then it doesn't feel like a resolution, just an abrupt brick wall.