"Martin, who has two more in the series to publish, said he would put it in if it lent itself to the plot. He said the books are narrated through his "viewpoint" characters, so he was more limited than the TV shows. "Frankly, it is the way I prefer to write fiction because that is the way all of us experience life. You're seeing me from your viewpoint, you're not seeing what someone over here is seeing.
Because none of the viewpoint characters are gay, there are no explicit gay sex scenes in the early books. "A television show doesn't have those limitations," he said. "Will that change? It might. I've had letters from fans who want me to present particularly an explicit male sex scene – most of the letters come from women." "
https://www.theguardian.com/books/2014/aug/11/george-rr-martin-game-of-thrones-gay-sex