There are subjects that we just don't discuss in polite company. Stuff like, drugs, murder, and sex are major no nos. That's why we have to start using phrases like "no nos" to describe what we mean. Taboo subjects, ironically are the subjects that bind us. They are universally human. They are subjects that ought to be discussed in storytelling. The question is how.
When you talk about these things explicitly, they become pornographic. When you use euphemisms to avoid it, you are Bowdlerizing. So again, how do you avoid being licentious or pussyfooting?
I find the best thing to do is not care about it. Make these things secondary. Instead of a scene about characters having sex in an apartment, make the scene about the apartment, and the people having sex is simply one part of the scene as a whole.
Nothing is foolproof, though. You cannot stop your audience from thinking what they will think. Some people think that anything even remotely pertaining to sexuality is pornographic. There's nothing you can do about them (unless you want to just completely avoid the subject forever). But for everybody else, you can just act like a simple, rational adult, and treat the subject like you treat any other subject.