The Game of Thrones that we watch on HBO has never felt completely beholden to the books. We've known this ever since the first season, when Khal Drogo ripped the throat out of a character that George R.R. Martin stated would be important later. Characters such as Strong Belwas and the Brave Company were never introduced, though were arguably minor and able to be written around.
However, with this newest season, the changes have been getting bolder and more substantive. Jaime arriving in King's Landing well before he was supposed to. The breakup between Tyrion and Shae not leaving the former with reason enough to commit murder (though I guess that's subjective). Jaime raping Cersei in the Sept. And in this latest episode, it seems like the writers just decided to throw the book out the window. For instance: