Because he thinks that he is bad for Bella and that as long as he's around her she will be in danger.
Forks, Washington
because he thinks that Bella is in too much danger with him in the story.
Forks is in Washington.
Edward thought that he was protecting her by leaving her. He didn't want to put her in danger of his family or any vampires. Later in 'New Moon' he thinks that Bella is dead, and turns to the Vulturi to die too. Bella saves him and they return to Forks, Washington.
In the woods behind her house in Fork's Washington.
Forks Washington
Forks, Washington and La Push, Washington
Washington, Forks but Bella moves in between La Push & Forks =)
Forks Washington La Push Washington and Volterra Italy
Forks ,Washington/ La Push
The Cullen family left Forks in "New Moon" to protect Bella from their dangerous lifestyle as vampires, especially after an incident at Bella's birthday party where she was almost attacked. They believed it was in Bella's best interest for them to leave and distance themselves from her for her safety.
Yes, in New Moon, Edward left Bella and left Forks completely. Bella, Edward and Alice are in Italy at the end of the book too. Also in Twilight, Bella and the Cullen family go to Phoenix. In Breaking Dawn - Bella and Edward's honeymoon is out of Forks too at and island called Isle Esme. If you are wondering if they ever leave after the forth book, that is up to your imagination. You can imagine them staying at the Cullens' permanent resident in Forks but you also have to take into consideration that Carlisle is not aging and he has to look older the longer he stays as a doctor in Forks. I would belive that, after a decade or so, Edward and Bella would move onto different places--perhaps college.