I have found when writing a synopsis it can be difficult to remain focused on the romance between the hero and heroine. I can get so caught up in trying to get from point A to point B in my plot that I miss what is most important in a romance, the relationship between the main characters.
I have finally come up with a method to help me keep my synopsis focused on the romance instead of the details of the plot. I start with a character sketch of the hero and heroine, giving any background information pertaining to the story as well as character traits and flaws. Then I concentrate on the conflict between them both internally and externally and how it progresses through the story. After that I write out the resolution of the conflict, showing the black moment and how the main characters come together in the end.
After I finish writing those areas down, I usually have two pages single spaced. For some editors that is all they want. If you have an editor who wants more, it is easy to go in and elaborate on the progression of the story, keeping in mind the conflicts that separate our protagonists and how they build toward the black moment and its resolution.