Ok...if you really want to know why; He left because he thought his life wasn't the right one for Bella. The incident with Jasper at her birthday party had him think what could truly be best for her, so he made the decision to leave her life so she "could be happy". Hope this comment helps.
this question is so dumb. if you were a twilight saga fan you'd know the answer already. how's this for an answer: edward thought bella killed herself so he went to the volturi to ask to die. they killed him. then bella showed up with alice.they saw bella's prmise turned her and she was a sheild. alice joined too. then they had a lesbian threesome with jane then gang banged with all the men. THE END
