In regards to ending a story a writer from Parks and Recreation had this to say: "The ending of a story should be both tragic and inevitable" It's from the book "Poking the Dead Frog" and I'll have to look up which writer said it. But it really really struck a chord with me because this is EXACTLY how all of my favorite stories end (although I wouldn't have been able to express it so eloquently) . It also happens to be very direct yet open enough for writers to interpret as they wish. I think it's a great piece of advice.
I'd like to see the context of that quotation. Given that the end of life is both tragic and inevitable, I can see a kind of biologic necessity in that statement -- but stories? I'd like to add "tragic, inevitable, but with the possibility of redemption. By redemption, I mean that the protagonist has in some way changed, thus pushing back the dark just a little more.