From Men of Romance:
In Parallel Plots, each player takes on the role of a hero and play explores their romantic relationship with their own heroine. The heroes and heroines do not directly interact in any scenes, but the scenario chosen should allow for indirect connections between the four story lines. Players take on specific roles during other players' scenes, creating four separate yet linked romance plots.
Parallel Plots is structured as a series of scenes between each hero and his own heroine.
Players should create hero characters and then create a heroine character for the player on their left, or the other three players can brainstorm each heroine in turn. As a group, decide on the scenario.
Play consists of three scenes focused on each hero and heroine, for each player. So player 1 will have a scene, then players 2, 3 and 4, then player 1 will have their second scene. Play continues until each player has had three scenes and then there can be short optional summary scenes if the Happy Ever Afters aren't yet established.