You said, "I think it's true to a point." This doesn't make it clear what you think the "true point" is. Perhaps it was showing faked sex on screen acts, or, in the text, descriptions of sex acts.
Perhaps you meant that you think a nihilistic (fictional) universe is more "adult" than one with a vision of eternal absolutes.
Maybe it was something I haven't thought of.
See my tagline. To a very considerable extent, the world is what we choose to see in it.
If squalid sex and lust for power and dishonor and betrayal is all you believe exists, that’s all you’re likely to see in the world around you. From my limited exposure to GOT, that’s the world Martin sees and the one he portrays in his books. From what I hear, that is exaggerated even more in the TV series.
OTOH, I personally believe there are higher and deeper things, things that ARE worth fighting for.
Sam: I know. It’s all wrong. By rights we shouldn’t even be here. But we are. It’s like in the great stories, Mr. Frodo. The ones that really mattered. Full of darkness and danger, they were. And sometimes you didn’t want to know the end. Because how could the end be happy? How could the world go back to the way it was when so much bad had happened? But in the end, it’s only a passing thing, this shadow. Even darkness must pass. A new day will come. And when the sun shines it will shine out the clearer. Those were the stories that stayed with you. That meant something, even if you were too small to understand why. But I think, Mr. Frodo, I do understand. I know now. Folk in those stories had lots of chances of turning back, only they didn’t. They kept going. Because they were holding on to something.
Frodo: What are we holding onto, Sam?
Sam: That there’s some good in this world, Mr. Frodo... and it’s worth fighting for.
From my limited perspective on GOT, there really isn’t any Good in the world, and there is nothing worth fighting for except personal power and pleasure. Not a world I prefer to live in.
A fair comment. I'm guilty of not developing my thoughts clearly enough and I thank you for pointing it out.
The sex in GoT is over the top in my view. Your second paragraph is a pretty close summation of my actual thought on this so I will let it stand with my thanks.
Just look at DC these days. Tell me there aren't power struggles of a similar nature behind the scenes, just without the overt bloodshed.