First a little history. Years ago I belonged to a small writing group in Washington, DC. I was having the group critique a novel I was working on, feeding them no more than 30 pages each month. Finally, one member of the group was bold enough to tell me either to allow my characters to get it on and make out or drop that story line but she was tired of all the teasing. The dam had a leak and suddenly it was broken. Another member jumped on the band-wagon to inform me either have a battle or not have one but don't lead up to a battle only to let it fizzle out.
In other words, I had two story lines which my readers weren't enjoying. One was the to-be intimate romance between my lead characters. The other was a major battle. So, taking the bull by the horns, I attacked the battle issue and let it begin but to avoid any major descriptions, I sent my lead character to another dimension. The sex, well, I was reluctant to have any erotica in my fantasy but I still wanted that sexual tension. It was issue but I was able to find a happy mixture.
Until my paid editor ripped it apart. The battle scene was a cop-out. My editor told me bluntly - either remove the battle option from the book or write the damned thing. Don't send your character to another dimension to avoid the battle. Strangely, she was okay with the sex aspect and thought I'd held the interest while keeping the story line moving but it still could use a little more 'ompf' to make it stronger.
To get the battle scene proper I imposed on a friend to give me some sword fighting lessons. Needless to say, we had to do this outside where the whole world could watch me do - his words, not mine - the monkey dance. We used bamboo swords for my protection until I got the hang of it. My one son filmed it but that was a futile effort since he was laughing so hard the camera he held jiggled all around. The neighborhood group of boys stood in the cul-de-sac and watched Mr. Nailor do his yip-yowl monkey dance. When I had finally gotten my steps learned, we moved to real metal swords and I finally knew what it meant to feel the grip in my hand, to relish the ring of metal as the swords came together and one would slide down the other. It was exhilarating. I learned how to write a sword-fighting scene and hence, a battle scene. Still, I didn't know exactly how it would feel to impale a person. Unfortunately, I wouldn't — or should I say fortunately I didn't need that experience. An undertaker friend explained to me how it would feel and the difficulty. To say the blade pierced like a hot knife into butter is not totally accurate.
As to the sex. I was on my own, for the most part since my wife was adamant that I couldn't hire somebody. I had to go with my gut and what I knew.
But the truth was, either my character had to stay and play or I had to eliminate the story line of intimate sex. A reader will only go along with the tease a few times before putting the book down. This doesn't mean you need to go 'all out' and have an explicit sex manual. As I told my friend a few days ago when we were discussing writing sex:
Studs know how to be sexy because they have conquered. Sensual women know how to lure because they have seduced successfully. A virgin can only know so much and then she is no longer a virgin but a scared little girl who now knows the truth. Your heroine can vamp just so far before it is out of her realm of expertise. Think of it as a innocent girl who performs her first lap dance. She can do the moves and be sexy. She can grind on the man. But, at some point, she is going to be surprised when the man becomes aroused. She will probably stop her first lap dance. On her 2nd or 3rd lap dance she will continue until the man reaches the point of no return and again, she is going to be surprised. AT THAT POINT, the innocent girl is no longer innocent. She might still be a virgin but only technically. She is now a woman of the world with only the actual act to complete the full transformation.
A writer doesn't have to give every detail of the love-making act. There is an art to writing a sex scene that will appease the reader. Remember that first move for a boy from his hand on her shoulder to awkwardly fumbling against her breast? It is sex that every reader can identify with and that is what you want. You don't need to describe bedroom acrobatics to satisfy the reader unless you are writing extreme erotica or porn where it is expected. My friend, Mitch Whitington, wrote a fantastic article on how to write sex as 'afterglow' which really defines the moment. You can read that here.
Also, to build up your arsenal of how to write war and sex. Use the proper word. A battle scene is not an engagement. The combatants are not a love-struck couple going ga-ga over a ring. It is a bloody, brutal and vicious event. It is not to be glorified. Death is final. As for sex. There are many synonyms for the sexual organs but as one writer told me at a symposium, call it what it is if you're going to call it anything. Also, avoid all the colorful adjectives. As he said - throbbing and juicy are heavily over-used. Or as the chaplain so aptly told us when I first joined the Navy and was going through boot camp: Most of you young men are eighteen or older. You no longer go wee-wee or poo-poo so quit giggling like a 16-yr old virgin girl when somebody uses what you think to be a cuss-word. Body functions and the Vietnam War are real.
So, to paraphrase that colorful chaplain: War and sex are real. Write it real.