Romantic tension is one of those wet angry cats we juggle even if we aren’t writing a romance book. Don’t dismiss romantic elements so quickly. If you have any type of relationship budding in your stories, use it. It can only add depth as a sub-plot. The love doesn’t need to be a blazing inferno. It can be a smoldering flame that builds slowly over time (or series).
Keep them apart – Something always keeps the lovers apart until the end. It can be a physical separation, mental or emotional. Whatever it is, they can’t fulfill their romantic destiny until the resolution of the story.
Love is earned – They can’t fall for each other without earning the affection of the other. Allow one or both characters to play hero. In some way he has to be there for her when she needs someone. The characters should prove to the reader with their actions that they deserve one another. He doesn’t need to be the hero that saves the world, but he does need to be her hero.
Throw a character a curveball – The lovers don’t need to be opposites, but it helps define tension when one has qualities the other doesn’t. The characters will need to adapt to the interactions. Maybe she is impulsive and he is deliberate. It can put your characters in a tizzy when they are together.
Altruistic actions – Nothing says love like being there and doing something for the other without expecting or asking for anything in return. They are there for one another because they want to only love the other. They may not even realize it at the time. Your character will be trying to guess the motivations of the other. At the end, they’ll know it was because they loved each other.
Capture their thoughts – He’s holding his hands behind his back but readers need to know it is because he wants to touch her. Don’t skimp on the inner conflict.
Throw interruptions at them – TV Shows use this a lot. The would-be couple locks eyes and are about to kiss for the first time, when someone bursts into the room for an unrelated matter. The couple gets shocked back into reality where they pry themselves apart and attempt to act as if nothing was going to happen. Naturally, their thoughts and hearts are racing while they look calm on the outside.
One taste and they’re hooked – After that very brief kiss, they can’t stop thinking about the other. When the lovers are apart, they are always in each other’s thoughts. They become aware of themselves when their interest is present. Maybe she blushes while his hands get clammy.
Nothing is perfect – If you think the characters need to be perfect in their interactions, need to be flawless, you’d be wrong. You aren’t writing about an ideal lover in an ideal situation. You’re writing about your character’s ideal. A little reality by making him clumsy or the situation awkward is not a deal breaker for the reader. We find it endearing.
Game players – A very easy way to subtly imply romantic tension is have the characters almost one up each other in every scene. It can be through body language like she smirks at him as she leaves the room and has him wondering what she is up to now. It can be verbal where he wins an argument, proving her wrong.
Make it meaningful – The test of true romantic tension is if you can take it out and the story is fine, then it isn’t romance. Romance is all about the emotion. Every single romantic situation should change the characters. Maybe because of the attraction he feels he can open up to her. She feels she can trust him. It can complicate things and make the action in the plot dire. She’s scared and doesn’t want to get close to anyone, so she runs off when he was helping to protect her. The emotion must impact the characters, no way around this.
I get my ideas from sitcoms. Frasier is an excellent example with Niles and Daphne. If you need inspiration on how to create romantic tension find a sitcom to watch.
If you want an example of page clenching romantic tension dissect Twilight by Meyer. It doesn’t matter what you may think of her plot or writing. She masterfully crafted some intense romantic tension through four books that had females everywhere swooning.
Whatever genre you write, romantic tension can help your reader invest in your characters and story. They don’t call them book boyfriends for nothing.