Well, I do recall the Jamie/Cersei rape causing a hoopla at least as big, but this time it wasn't even rape and yet we get senators calling for boycotts.
Even if it was indisputably rape:
Rapes happen. Bad stuff happens. What's wrong with a fictional show that depicts bad stuff happening? Is it all supposed to be flowers and happy happy gumdrop factories?! You can't tell a story that involves bad stuff happening? Why the Hell not?!
I think it's more the fact that the writers keep on going to rape over and over as a plot device, or hell -- even showing random red shirts in the background getting raped. it doesn't bother me personally, but I can't argue when I hear female GoT fans complaining about how rape-y the show is.
hell, is there a major living female character on the show who hasn't been subject to "non-consensual sex" other than Arya and Brienne?