For instance, my friend writes science fiction. Admittedly, there is a touch of romance there, but he's writing what I would call a "serial" romance; the romance takes place over the course of three or four books, but does eventually have an HEA after much fighting (mostly of bad guys) and the occasional misunderstanding. In no way would I term his novel(s) romances; they are science fiction with a subgenre of romance. The heat level in the love scenes is very low, mostly because that isn't the focus of his story, and there is a high probability that the HEA will not be what anyone expects.
In order for a novel to qualify as a romance (with a subgenre, like science fiction, or without one), there needs to be an untouchable HEA. These two (or three), after trials and tribulations, are mated for life; what the writer has put together, let not the writer pull asunder. Even if it's twenty-five years later, or three hundred years later; messing with the reader's characters can turn a romance reader off faster than a naked Lyle Lovett.
The readers of romances don't mind the occasional serial romance, as long as they know in the end they'll get their HEA. But if they know that all of that emotional investment they put into this couple turns into something else, whether the romance ends with a bang or a fizzle, they're gonna be ticked.
According to Wikipedia (God, I love Wikipedia), "A romance novel is a literary genre developed in Western culture, mainly in English-speaking countries. Novels in this genre place their primary focus on the relationship and romantic love between two people, and must have an "emotionally satisfying and optimistic ending." Through the late 20th and early 21st centuries, these novels are commercially published in two main varieties: category romances, which are shorter books with a one-month shelf-life, and single-title romances, which are generally longer with a longer shelf-life. Separate from their type, a romance novel can exist within one of many subgenres, including contemporary, historical, and paranormal."
A few things need to happen for a romance to be a romance, in my opinion:
1) They need to be attracted to each other. Yeah, I know, but you'd be surprised at the number of books I've read where they start out with no attraction, and gradually build it. If it's done correctly, it can be fun, but for the most part if the chemistry isn't there from the start then it won't work for me. It pulls me out of the story, makes me question the book's "reality" too much to have them grow into each other. The only time it's worked for me is if the heroine (or hero!) has loved for a while, but the significant other was in another relationship and didn't realize how said heroine (or hero) felt. Lori Foster's Too Much Temptation is a good example; Noah has no clue how he feels about Grace until after he breaks up with his fiancee.
2) There need to be a few bumps on the Yellow Brick Road. Getting together, saying "I love you" and cutting to the cute end scene doesn't really work. There need to be a few bumps in the road, a few lumps in the mashed potatoes, a small lump of coal in the candy in your stocking. In other words, don't make it so easy that the reader is bored. Now, I have a hard time writing a story where the heroine is full of angst, and I admit that. I tend to throw in outside forces to keep my heroes and heroines apart. That works just fine for me. I just have to be careful and make sure there's an outside influence keeping them apart, or threatening them in some way. But if you want good internal forces keeping people apart, then I recommend Linda Winfree. Her What Mattered Most is a prime example of what internal forces can keep a couple from finding a happily ever after until the very end of the novel. Lauren Dane's TriMates is a good example of outside forces working against a couple (or in this case, a triple).
3) Love is about more than sex. You need proof of this? Look at what's been happening to Anita Blake. I love a hot and heavy sex scene, but I love it more when the two (or three!) people involved are romantically entwined. Again, Lauren Dane's TriMates is a prime example of this. Three people forming a bond together and making it work can be truly hot. Tracy, Nick and Gabe's bond is very strong, and very loving.
Sex without the beginnings of love is not my cup of tea. Now, I've seen "sharing" romances where the hero gets off on sharing his woman. But even there, the love is paramount to the story. The hero loves the heroine, and they will, together or with company, ride off into the sunset for their happily ever after.It can work for me... or it can turn me off completely (as in the case of Anita), depending on how it's done.
4) Parted lovers should reunite. Okay, if there was cheating involved, a) it should be handled early on, preferrably as a past act, and b) you can't make it easy to return to the lost love. If the government has wisked your lover away to be in the witness protection program towards the end of the book, either the trial needs a speedy end or the feds need to snag you up and take you to your lover just so he/she will stop whining and driving them insane.
One of the most poignant "parted lovers" stories I've ever read was where an angel of death needed a lesson in opening her heart back up again. She's turned human and sent to deal with a man who she thinks is going to die in a crash. She saves his life, only to find out later he's dying anyway. She holds him in her arms as he passes away. Because she's an angel of death, she's able to prove to the powers that be that she's reopened her heart, and is reunited with her lover. Very few things make me cry, but this story was so well written that this one did. I'd give you the name of the story and the author but damn it, I can't find it. I'll post it as soon as I do.
You'll thank me for it.
5) If you kill off the hero/heroine, expect to reap the "rewards", even if it's six books later. Romance readers are extremely loyal to "their" couples. Killing off their couples makes them mad. Don't do it, man! Just don't do it! It won't be pretty. Trust me. There isn't enough chocolate in the world to make it better. Romance lovers are fanatic about this kind of thing. If you're going to have the doomed love, then have it be the secondary story. Tell it from the point of view of a different couple, who in turn are grateful that their romance didn't turn out that way. (And, if you must write it, make sure that the "doom" can be reversed, or at least show them happily reunited in the afterlife. Or reincarnated into a different life where things work out for them, as long as things ultimately work out for them.)
I'm sure there are things that I'm forgetting here. It's nine a.m. and I'm only working off of one cup of caffeine, so my brain is only working at half speed. But for me, these are the basic elements of the romance story. Let me know if you can think of anything else, and I'll add it to the list if I agree, or at least chat about it if I don't.
Now for my second cup of tea...