I've read Brandon Sanderson's Mistborn and Stormlight Archive series, and I noticed that there are hardly any (if any) references to sexual activity between characters. I find that the author paints otherwise very gritty, full, and realistic pictures of characters' behavior and psychology—covering basically all aspects of the human condition except for sex. Is that deliberate, or am I missing something?
Brandon Sanderson is a practicing Mormon, a religion which is not big on glorifying sex. He kind of commented on this in his site's FAQ entry about why violence and swearing exists in his books.
My books are about hope, in my opinion. Hope, struggle, and victory. I’ve tried very hard to keep graphic descriptions out of my books where I can, but I can’t always do so without undermining the story.
A wise friend (an LDS writer) once explained that in his opinion, glorifying violence or sexuality comes when consequences are removed. The scriptures themselves don’t shy away from graphic content or descriptions (scalps on swords, anyone?) The important issue, however, is that the scriptures show the destructive effect that these things can have, even on the good people who are forced to engage in them.
And here is a more direct quote regarding sex (bolding mine):
Storytime. When I was working on Mistborn 2 with my editor, he asked me, "Are Vin and Elend sleeping together?" I said, "Absolutely." He requested some confirmation of it on the page, and I explained something that has always been my policy, and one that has served me well. I consider what I'm writing to be a very detailed script, which you the reader direct in your mind. Each person's version of the books will be slightly different, but in sometimes telling ways. The subtext of conversations will change, the visualizations of the characters, even larger implications are changed, distorted, and played with by the reader as they build the story in their imagination. This is an area in which I prefer to leave the answers to the reader. For those who wish to imagine that the characters are having sex, then the implications are often there. (Though I've gotten better at that balance, I feel.) For those who don't want to imagine it, and wish to pretend the characters are living different standards, I will often leave the opportunity for that--unless it is a plot point I consider relevant. Certainly, my upbringing and beliefs are an influence on this. I'm obviously more circumspect in these areas than I am in others. But yes, for those who don't want to pretend otherwise, Vin and Elend were sleeping together. And Wax and Lessie never had a real ceremony. My editor tried to remove the word "wife" from one of the later books, and I insisted, as the shift in Wax's thinking was a deliberate point on my part--related to his changing psychology in the books. But even to him, it's more a 'common law wife' thing. As a side note you'll likely find amusing, I do get a surprising number of emails from people who complain to me (even take me to task) for the amount of objectionable material I include in my books, and ask me why I have to wallow in filth as much as I do. I'm always bemused by this, as I doubt they have any idea how the books are perceived in this area by the general fantasy reading world...
And ultimately, it may just be personal preference. I'm listening to some of his Writing Excuses podcast episodes with the sex-scenes tag, but it may just be something that he doesn't find easy to write.
Shanna Germain joins Brandon, Mary, and Howard in front of a live audience at GenCon Indy to talk about writing love scenes. They’re not easy to get right, and they can be even more difficult to talk about it in a way that leaves the Writing Excuses team’s “clean” rating intact.
In fact, he delegates most of the episode to Shanna in the Season 7 episode because, to quote him, "I am a prude". In Season 8, Episode 1, he specifically states that he prefers the offhand mention that activities were going on without getting into detail, although he respects people who can make such activities an integral part of the story.