It's actually a really interesting point, because while Sansa obviously didn't want to have sex with Ramsay for the normal reasons (i.e. for pleasure because she's attracted to him), she was definitely aware of what Littlefinger told her about how she needs to take charge of her own circumstances instead of being pushed around by other people. Look how much influence Cercei managed to amass by using her cunt as a weapon - I doubt she enjoyed the act itself, but how can you class it as rape when she deliberately fucks people to get what she wants?

Also highly ironic that this kind of discussion/analysis would NEVER be possible among feminists, who claim to be the authority on rape. For them everything is just a black and white issue, no questions asked.