Why does Edward break up with Bella?

Answer 1

To keep her from the dangers of his life. To stop him endangering her life.
Because Edward was under the impression that if he left Bella behind, she would have a chance at a normal human life rather than being stalked by the supernatural for the rest of her life.

Answer 2

Edward is terrified that he is putting Bella in constant danger by his presence and the amount of time she is spending in "his world." He does not want her to become a vampire for fear of her losing her soul and becoming one of the eternally damned but leaving her human when she is so exposed to the vampire world is not a reasonable solution either. He believes the best way to protect her is to remove himself and force her back into the human world.

Answer 3

Edward leaves her because he needs to protect Bella from him and the rest of the Cullens. It's not that he'd hurt her but It's dangerous to always be around a vampire.
He loves her though, so its hard for Edward to.

Answer 4

They do not break up in Eclipse. Edward leaves Bella to protect her in New Moon.

Answer 5

because he wants to protect her but only misses her as much as she misses him, they find out that they just can not live without each other!

Answer 6

Because Bella forced him to change her if they got married, but Edward didn't want to change her.