But haven't you ever wondered why you're on the edge of your seat, demanding your favorite love interests get on with it already? It's an emotionally manipulative process for sure, but nothing wrong with that. So with a big acknowledgment to where this material originates from, here is the "12 Steps to Intimacy" written by Nancy Odell and reposted as a simple list by Angela Quarles in regards to why it's so steamy between love interests Eric and Sookie on True Blood.
Here is also a point I made to the author. Sometimes the sexiest thing doesn't even involve sex or exposure to nudity. Sometimes the sexiest thing is a small, intimate gesture or touch. It's the longing and anticipation it builds up. So let me take two simple examples.
The Lover -- in the film adaption who can forget the car ride where Jane March's character and the "Chinaman" (as she calls him) touch fingers? It wasn't anything more than a forbidden touch of fingers no less. Yet by the time she gets out of the car, you want them to jump each other. That simple clandestine moment became infamous and used in other films.
Sense and Sensibility -- the longing and looks between Emma Thompson's character and Hugh Grant's character were all we got to see for an entire film. These two never touch each other. They talk and take walks together and many, many looks pass, but no kissing or sex. It's a completely chaste courtship, but you want them together none the less.
True Blood -- Eric and Sookie took essentially three seasons to build up to their romance. The first season was a lot of looks passing between them. In season two, the looks escalated and the "dreams" sequences commenced. Yet we still didn't get to see them in real life until season four. Even then Alan Ball doesn't immediately give us the payoff. We spend a lot of time on more looks -- and Alexander Skarsgård plays longing and vulnerable really well. The look on his face in the episode when she introduces and leave him in his "cubbie" to attend "human stuff" was pure longing.
My point in these descriptions. Notice the sexual tension does not involve actual sex. The tension is the build up. And build up requires work in your writing. You cannot make characters meet (unless there is a no purpose involved in the storytelling) and then just go at it. Classic love interests play on the readers or viewer's emotions. We want our lovers to consummate all that desire -- that's the payoff. But you can't shove them together in two or three pages and expect the audience to having rooting value for them.
One more note: the way you go about building that tension and how you tactically apply it sends other messages about the nature of the character's relationship. I pointed out that in my book California Girl Chronicles, the tension between love interests Drew is always a bit twisted, as is the nature of their relationship. When he "looms" over her that is about sexual dominance -- and he is the bad boy love interest. So pay attention to the kind of tension you build and how you build it to make a statement about the relationship too.