H is for HEA. Or, HFN, depending on your story arc and if your work is part of a series. LOL, don't freak out. I can explain it all.
HEA is short for Happily Ever After. If you write for some publishers, such as Harlequin, Avon Romance, or Harper Collins, the HEA is a compulsory component. If your character doesn't get the girl or man of his or her dreams, you either cannot publish with them or you need to rewrite the ending.
HEA is a staple of your writing diet if you are a romance author, a historical fiction writer, or a writer of any genre where the romance is the compelling factor. Now, I write several different genres and in all of them, romance has a part. But, the compelling part of my stories is not necessarily the lovey-dovey. In my paranormals, the magic is the kicker. The horrors, well, the horror is the best part. But, there is always a little romance in there. In most cases, my character's unexplainable and sometimes annoying desire for someone is the one thing that makes them human, that fleshes out their stories and brings them to life for the reader. Longing, desire, coveting...these are all uniquely human traits. Animals don't do that. We do.
So, what then, is HFN. Easy. Happy for Now. This is great for a series where you plan to maybe kill off the character, or have your heroine land in the arms of the decidedly roguish man and not the steadfast one who seemed so perfect for her in the beginning. But, will he remain faithful? Ah, that is the question for an HFN novel.
As a horror writer, I prefer a little-known acronym: HNE. Happily never after. *giggles evilly*