Arnold Schwarzenegger is dragging his feet in his divorce with Maria Shriver, sources close to the couple tell TMZ, and the question is 'why?'.

Maria filed for divorce in July 2011 -- more than 4 YEARS ago. We're told the financial settlement was worked out a long time ago, and all that remains is a sign off. As we reported, there is no prenup, so they're splitting up roughly $400 million.

Our sources say there are no remaining issues, except a simple sign off, but that hasn't happened. As one source put it, "Whenever Maria says she wants to move on with her life, Arnold drags his feet."

Another source says it's not like either needs the divorce for financial reason ... they both have access to more than enough to pay the rent.