Bella changed,she wasn't the old bella. Not the one he remembered. In breaking Dawn Bella wasn't the same really. She was very maternal ... and her personality had changed drastically. She clearly changed her opinion about the way she felt for Jacob feeling আরো for Edward. When she was human she was afraid,she didn't want to hurt Jacob his pain was her pain. He cared too much about him. Since she had became a vampire she realised how much he loved Edward. Jacob didn't find the Bella he loved. For him if she became a vampire she was dead .
Because isn't in the first book jacob says: "I'll always remember আপনি like this way, পরাকাষ্ঠা cheeks. Heartbeat.Two Left Foot. All of that" And Bella also mentioned Jacob at the Third book after the ALMOST fight with the volturi she said: "I tried to ignore the impressed looks, mostly keeping my eyes on Nessie's sleeping face and Jacob's unchanged expression. I would only be just Bella to him, and that was a relief." And besides, Jacob didn't want Bella to become a vampire from the very start. :) (JaazieC.)