1. Strong CharactersThis is vital for all fiction, but especially so for romfic. This is because the reader must fall in love with one of your main characters. Would Mr Darcy have set readers’ hearts aflame if he were a silly cad with no redeeming qualities? Absolutely not. He was a judicious gentleman of impressive intelligence and refinement who secreted away a tender heart. You want Elizabeth and Darcy to end up together because that means you get to end up with him as well, and a character must be dynamic and three-dimensional, otherwise who will fall in love with them? Your characters need to have traits that compete against each other. They must realize and struggle against their worst qualities for the sake of love.
2. PassionOnce you have strong characters, stick them together with a generous dollop of passion. If characters are really in love, a sense of passion should also be provoked within the reader – they need to feel the depth of your characters’ emotions for one another. Passion measures this depth and is the rubber band that you tie around them. No matter how hard they pull and stretch apart, that passion will bring them back together in the end.
Passion also means that your characters must fall for each other, hard. They can play around with the idea and question their true feelings, but the reader must know that, when push comes to shove, their love is unquestionably genuine.
Dialogue is essential in communicating this. Professions of love are acts of passion. A character is exposing their vulnerability during these moments of confession, articulating their deepest feelings. ‘Hey, I love you,’ just doesn’t cut it. They need to reach down deep and lay their beating heart on the table.
3. Obstacles.Now that you’ve tied the passion band around your characters, toss in a liberal amount of obstacles to test its elasticity and your characters’ resolve. This can be in the form of an antagonist – in love stories, sometimes the best antagonists are the couple themselves – or a circumstance which makes being together impossible.
An effective obstacle is separation. They say absence makes the heart grow fonder, but your love-struck protagonists don't know that. Our star-crossed lovers must attempt to live without each other and then come to realize that, no matter ho hard things are while together, it's impossible to stay apart (think Tristan & Isolde, Romeo & Juliet, Pride & Prejudice, even Twilight for goodness sake). During this separation, the obstacles are the characters themselves. They think that, by being apart, because they're angry at each other or because they feel it's "for the best," they can dismiss their feelings. But never underestimate the power of that rubber ban of passion.