Romance is hard to write because there are so many romance writers out there. Some write raunchy romance; some write historical romance; some write traditional girl meets boy, girl hates boy, girl suddenly likes boy, they get married.
I think the key to writing a good romance is to develop really fascinating characters. The reader has to feel strongly for the two main characters, though they both have to have noticeable flaws. The reader has to want the couple to work out. And there have to be plausible obstacles.
But romance also has to follow the Three-Act structure. In the first act, all the players, the conflicts, and the dreams of the characters have to be introduced. In the second act everything has to fall to pieces. And in the third act the hero or heroine shows who they really are, and someone has to get together.
I strongly recommend writers outline their stories. Break up your outline into three acts. Break up each act into a certain number of chapters, maybe 10 – 15 chapters for the first act; 8 – 12 for the second act; and 10 – 15 for the third act. When I write, my chapters tend to be short–1500 to 2000 words–so I aim for a total of about 35 chapters in my outlines, and my first draft tends to expand that to 40 or 50 chapters. Pacing is also important. Some sections of your book need to sprint, while others can be more reflective (though not for too long).
A large portion of the books I edit are romances. I can help you develop your story, copy edit your first draft, or proofread after your beta readers have given you feedback on your third draft.
Contact me at firstname.lastname@example.org.