One of the periodic issues that raises its head is the Happily Ever After and why a romance has to have one.
It always amazes me. People don't want an emotionally satisfying ending? They don't want the major plot arc resolved?
If all that happens in your book is that the people take up the threads of their ordinary life at the end, it does not work. It is the sort of -- it was all a dream. Characters need to grow and change.
Because Romance belongs to the archplot category of genres, it does mean at the end of a story, all major threads should be tied up. In particular the spine of the story must be resolved. Time has shown that a greater percentage of the audience prefer a happy ever after.
Think of this another way -- would a crime novel be enjoyable if the killer was never caught, and the mystery went unsolved?
This is not a rule but a very important part of the form that has to be mastered. If a writer does not want to master this form, they are free to write in another genre. And there are other genres -- for example sagas where the romance is secondary and the spine of the book is held by the character's growth.
But if a writer DOES want to use the highly successful romance format, they do have to adhere to its most basic form.
The emotional satisfaction that readers get at the end is why people read romance. They want that buzz.
The real trick is to create a situation which gives the reader a white knuckle ride.She is positive until that last climatic scene that the principals won't get together. She wants that. And the writer should never cheat the reader. Well not if she wants her readers to come back for more.
For my part, I write historical ROMANCE and that means an emotionally satisfying ending with threads tied up.