Determine the theme of the love story. Themes for love stories can include unrequited romance, a romantic comedy, tragedy or an opposites-attract romance. A theme will determine what type of story the romance will involve and the type of characters that will be more suitable for that story.
Determine what characters will fit the story’s theme. The characters need to be suitable archetypes for the theme and have attributes that reveal their sexual and romantic attraction as well as push the plot forward. For instance, in an opposites-attract romance, the romantic couple can include two people who have opposite political values, but share a common interest, such as politics, that also brings them together. In "Romeo and Juliet," the young couple was provided with personal attributes that led to the play’s tragic ending.
Decide what obstacles the romantic couple will face. This can often be determined by the story’s theme. In an opposites-attract storyline, if the romantic couple have differing political views, then create obstacles that will heighten the tensions between the couple. For instance, one can be running for mayor, while the other is the campaign manager who works for his opponent. Not all obstacles are external. For instance, the characters’ internal flaws can create obstacles. In "Pride and Prejudice," Darcy and Elizabeth were unable to see how right they were for each other because of their prejudices.
Plot the story. Create scenes that reveal how these tensions pull the characters closer together. Therefore, make sure there are plenty of scenes that reveal the sexual attraction and closeness between the lovers. Give readers a reason to root for the characters. After determining the obstacles, create a number of plot points that will heighten the tension for the couples and keep them apart during the story. For instance, in the opposites-attract example, the campaign manager discovers information on her potential lover that could destroy his campaign. How she deals with this information will heighten the tension and force the characters to respond in ways that will push the plot forward.
Choose an ending for the story. Some writers like to keep endings open-ended while writing. But it doesn’t hurt to have a general idea of how to end the story. Romantic love stories generally end in two ways---either the couple overcomes their obstacles and end up together or they are unable to overcome their obstacles and break up. Some themes, such as tragedies, will have endings that are inevitable. Whatever the theme, choose an ending that will work best for the characters and the story.