The walking dead - Why did Shane die?

[Adam]

If any of you watch the walking dead series, you should know shane died at the end of season 2, and I was just wondering why would he die so early in the show? They're probably going to have another 8 or more seasons, and Shane won't be in any of them, well atleast I think. But what I wanted to ask was, why did shane have to die? Was he fired from the show so they had to kill him? Did he want to quit? Was this part of the story and he was going to die no matter what? Is he going to come back to life or as a zombie? If you have any answers or what you think please tell me.