It would be one of the biggest disappointments I've ever read. It wouldn't even make sense either considering the whole Twilight series was about Edward and Bella's love. "The lion and the lamb." How they grow and how the decision to be together isn't all sunshine and roses. It's difficult but for Bella, it was the right choice no matter what the consequences or costs were.
I'd probably end up hating Stephenie Meyer. I'd definitely throw some kind of tantrum. I'd just be down right pissed that I wasted my time reading four books to be thrown for a loop. Who likes loops anyway?