"How many promises does it take for someone to live each day?"
Even if people live closely alongside someone else, in the end they will live and die alone. All we can do in a world like this is to make sure that our feelings are the same - in other words, to make promises. What if those promises were to be broken? What if you still went on believing in that promise forever anyway? This is the theme that Fatal Frame II is based upon. It's not just a scary story, but a sad one as well.