Sex for the sake of sex is great in real life. Why not go for it just because you can? It’s fun and man it feels good… if you’re doing it right :p
In novels, however, it’s important that sex scenes serve some kind of purpose. The trick is, of course, ensuring that the joining still feels spontaneous and is enjoyed by all parties without spelling out the specifics of what the reader will learn from this particular scene.
So what kind of purpose? I hear you ask. “Isn’t sex simple supposed to titillate?” Well yes, it is, it’s supposed to illicit a carnal reaction from the reader. You should feel yourself a little warmer inside, and maybe a little naughtier too. But sex scene after sex scene without there being a greater purpose will fail to advance the story, which is what a romantic fiction novel should be all about – the narrative.
There’s no single purpose for sex in books. It’s not only about showing the physical progression of the relationship between characters. Sometimes it’s as much about the emotional advancement of that relationship too. In Explicit Instruction the reader can map the development of the sexual relationship between Flick and Rushe and see how that parallels the movement of their emotional connection. The sex is different and each experience between them reveals something else.
We can see how Rushe tries so desperately to keep Flick at a distance in the initial stages of their affair. We can see his rough and ready approach, and how he tries to treat Flick as just any other woman. But subtle changes are seen in each of their encounters until their affinity is undeniable.
Now it’s not simply enough for the writer to say, “Rushe wants to keep Flick at a distance and that is why he is so harsh with her…” Then progress at the end to, “Rushe has given up the fight and now realises that this dynamic, refreshing woman has wormed her way into his affections.” The writer must give the reader enough hints, enough small pieces of evidence, to link so that they can put the pieces together for themselves.
The great thing about writing Explicit Detail was further exploring that development between our main couple. The dirty talk and rough sex still exists but it’s there for a different reason now. It’s no longer about Rushe trying to push Flick away, it’s about them optimising the  pleasure of their partner. Playing together, keeping the variety alive while reminding each other of that undiluted passion they still feel for each other.
Some readers will no doubt disagree about the use or purpose of sex, some may even disagree with Rushe’s methods. But the sex is crucial to both books. Trust builds between them, and because of the nature of the sex that they have, that trust is intensified.
Rushe insists on consent but can be brutish. Flick has to trust him, she has to know that if he approaches her boundaries he will desist. She does trust him, because he always will. Being savage in bed, especially when he is overcome with want for her, is extremely arousing for Flick. She sees through his attempts to keep her at a distance and that teaches her more about this man. Just as her refusal to be deterred shows Rushe how determined, and committed she is to being at his side, thus, how she cares for him.
Flick isn’t going anywhere no matter how he pushes and Rushe only falls deeper when he begins to understand that she is truly accepting of who he is, primitive ways and all, she doesn’t want him to change, but she does want him.
There are many other uses for sex in books, sometimes it’s about gathering or showing information of a more material kind. It can serve a practical purpose, or a procreative one. The uses are boundless, it can be manipulation, or motivation, greed, impulse. But we should always learn something about the story or about the characters during these scenes, the journey doesn’t stop because the characters are enjoying themselves, it should always keep on going.

Good luck on your adventures,

xSx