By | July 05 2012 3:46 PM

Twilight fans hoping to see Robert Pattinson and Kristen Stewart play lovers in the film adaptation of 'Fifty Shades of Grey are going to be gravely disappointed. The fast-selling erotic trilogy (Fifty Shades Darker and Fifty Shades Freed are the book's sequels) has caused a casting debate with both stars at the forefront. Shockingly, the author is against casting the Twilight couple, who have been quietly dating for more than three years. Â