I could go on and on about the stereotypes that permeate every nook and cranny of ASOIAF, but that's well-worn territory. To me, here's the Key Quote: "I can describe an axe entering a human skull in great explicit detail and no one will blink twice at it. I provide a similar description, just as detailed, of a penis entering a vagina, and I get letters about it and people swearing off," [GRRM] said.
"To my mind this is kind of frustrating, it's madness. Ultimately, in the history of world, penises entering vaginas have given a lot of people a lot of pleasure; axes entering skulls, well, not so much."
George, allow me to clue you in: the reason why people write letters about it is because the way you describe penises and vaginas is often unbelievably creepy and unnecessary. The fights and battles in ASOIAF are often necessary occurrences, inevitable results of conflicts, backstabbings, politics, and the like. And I would argue that the gory descriptions are often necessary, especially when it comes to the lives & deaths of major characters. In your world of "Don't count them dead until you see the head," it's actually necessary for your readers to be given a definitive description that makes us say, "Okay, so that dude's gone." And hell, a lot of the time, that doesn't even matter, since now everybody can just rise from the dead if they want.
But sex? We get it, it's a part of the world, and the characters have to have it. And it causes problems in numerous ways. But if you can explain to me exactly why a reader would need a "just as detailed" description of a penis entering a vagina, then by all means, make your case. To me, it's just a bit creepy. Or at least weird. But maybe that's just me.