i'd say no...

it was outright rape, but they already have a fucked up relationshiop as it is, and who is to say it hadn't happened before and remained unmentioned in the books?? who's to say Cersei even feels "violated" in that day and age? ...in the books, after Jaimie came back and joff died, the twins were never quite the same...there's already a void between them i think this scene just more clearly shows why Jamie and Cersei aren't as thick as thieves in the upcoming future...i didn't like the scene but i got what they were going for in the end...

...it made me like Jaimie less on the show after he'd done some redeeming in the last season, but honestly, i only liked jaimie in the books when he was running around with Brienne..and no matter what happens to Cersei, i'll never really feel sorry for her...

..and let's be real, they ARE gonna greatly variate from the books at some point....Tyrion will go on trial and handle "dat bidness" before the end of this season....he'll be handling that other matter probably next season, and then what?? the next book probably won't be out by the end of NEXT season, so we will be seeing things change from what we know from the books...it was inevitable from the start