[quote=Dervish]
I don't think it's a case of people trying to pretend he's a good guy, for much of the stuff you said. He's still a largely immoral, egocentric sister-banging asshole who's done pretty much one redeeming thing in his entire life that he can't even talk about. I think the main issue people have is what I kind of outlined, which is it was just so damn jarring to how him and Cersei are portrayed in the books. Cersei to Jaime is everything and I can't really picture him deliberately being sexually violent towards her, at least not to THAT degree, you know? Just because he's guilty of a list of immoral things longer than my arm doesn't mean it's in his nature to do absolutely everything abhorrent, you know? It's kind of like if suddenly, Sandor Clegane turned around and raped Sansa or Arya. He's a cold blooded killer and a violent, absolutely unlikeable man (well, one of my favorite characters, but if we're speaking from an in-series perspective), but I can't imagine him ever doing anything like that, especially since his brother is the reigning champion of wartime atrocities.[/quote]

This isn't entirely relevant, but depending on your interpretation of a certain scene in Clash of Kings, Sandor does consider raping Sansa. I think it's interesting that you compare these two characters, since I feel they're more similar than almost any other two characters: both "knights" that disagree with the standard conventions of chivalry and knighthood that exist in Westeros, and only differ in their method of dealing with that issue. Sandor isn't trying to "redeem" himself, so I think that's why a lot of his immoral acts seem to be perfectly in character and "justified." Jaime is trying, at least somewhat, to make himself a better person, but I think at a base level he's just as big of a douche as Sandor (Moreso even), and that was displayed efficiently with the sept scene. 

[quote=Dervish]
Or if Jon Snow turned around and started bullying Sam Tarly to get the approval of his fellow Brothers. It's not that people are really offended by the act itself, because you kind of have to be used to it/ accept it as a part of the narrative to stick with it this far, it's just that how the scene in question was executed was a huge departure from the book and what people feel is Jaime's character. If they played it out more like the book, I don't think people would nearly mind as much. Keep in mind that a big part of Jaime and Cersei's narrative moving forward is how it becomes more and more clear that Cersei never loved Jaime, at least not to the extent he loved her, and was more or less using him, and him starting to discover that fact and distance himself from her, which becomes quite pivotal later on. He's proven to be entirely devoted to Cersei, and there's been nobody else, something he's pointed out on a few occasions. Just how that scene was executed just felt plain wrong and at odds with the book and blah blah blah, we're going around in circles. :PTL;DR Jaime's a terrible human being, but how that scene played out really didn't seem to reflect the character properly, especially compared to how it played out in the source material. He's capable of a great many crimes he needs to be held accountable for, but what was widely interpreted as a passionate act between two receptive parties who loved each other since birth should have never been portrayed as a cold, violent rape for reasons we've beat to death kind of like what happens later on in this season.
[/quote]

Cersei [i]was[/i] Jaime's everything, but just as you said, their relationship at this point is the slow realization by Jaime that Cersei truly is a terrible person, and is just using him. Does it not make sense that, given what we know about Jaime, that once he realized that truth his anger would manifest as violence? I find it quite believable. And what if they had played the scene out just as it was in the books? Honestly, it wouldn't have made any sense. At least in the book she had a reason to reciprocate: it was her reunion with Jaime, and that factored into it pretty heavily. How weird would it be if they actually had enjoyable, consensual sex next to the body of their dead child, in the middle of a church, just because? Though book readers would have probably said "oh hey neat" while watching that scene, I'd bet most show-watchers would've just been like "wtf, why?" That might have been in character for Jaime (who doesn't care about Joff and just wants to get laid), but it would've been way out of character for Cersei, and then we would've been having this discussion from a different perspective.