Bella should be with only Edward. Remember in breaking dawn when she is a vampire, aro says,"it's as if you were designed for this life." and also when the cullens are outside after the arm wrestle with emmitt, and the sun breaks through and bella is shinning and Edward is dazzled by bella , she talks about being a natural and it was as if she was born to be a vampire. I think it was destiny to be with Edward and nothing was going to stop it..
Exactly, I believe that is what Stephenie wanted us to believe Bella could only be with Edward. The puzzle always fit together with Edward. Jacob was a nice place filler when Edward wasn't around, but he could never fill Bella's heart the Edward did.