It was rape by today's standards. Not by fantasy Middle Ages' standards.
I think it has been pretty well established already that most noble houses pre-arrenge their marriage. Hell, sometimes the bride and broom barely knew each other beforre marrying (eg Catelyn and Eddard) and yet they had to consumate that same night. So what happened with Sansa was pretty normal within its context.
The problem here is that people are a) trying to apply today's moral standards to a fictional shows based in the Middle Ages, where violence has already been shown to be the norm, b) at the same time being rather hypocrites, because it is not the first time the series shows violence, sexual or otherwise. Just two episodes ago we were told how Bolton raped Ramsay's mother. Yet no one seemed to give half a crap.
We've seen children and babies being murdered by the dozens, beheadings, raping and attempt raping, killings of people and animals, killing pregnant women and their unbornt children, mass killings of people based on their ethnic origin (wildlings), slavery, sexual slavery, male genital mutilation, the list goes on.... but now this is the thing that outrages everybody? Something that hardly classifies as rape
on the context it is taking place? Of course it is rape if it happened to someone today. Of course marital rape is a pretty big issue. But we are not talking about today or here. We are in fucking Westeros in the fucking Middle Ages.
They say the scene was completely pointless and could've just implied it? When Robert's bastards were killed in season 2, they could also have just "implied" that a baby was killed in front of her mother. The scene had no point really, but still nobody complained.
Nobody really complained about how valuable scenes were until now and with this topic specifically. In my opinion, completely nonsense.
And the people threatening with quitting the show.... lol. People have been saying the same thing season after season (Eddard in S01E09, Red Wedding in S03E09, Oberyn's fate in S04E08). They can leave or not, but I do not think it's going to have a big impact on the show's ratings.
/rant