Romance: The second oldest form of fiction known (the first is the heroic fantasy quest). Ancient Greek novels were based on lovers separated by misunderstandings and adventures.
Like specfi, this has a huge number of sub-genres. Containing a love story is insufficient for a story to be “a romance.” As a sales tag, in romance, lovers don’t part at the end with warm understanding or sudden death. The romance has to be half of the weight of the story or more, and the other half, whether mystery, thriller, quest, etc. has to move the romance forward, not happen in isolation from it. A romance needs to end on a positive note, not only of the lovers together, but with a sense of justice in the universe. Otherwise, sell it as litfi or mainstream or specfi or whatever it’s close to. Women’s fiction is often a good choice if you don’t like the limitations of the romance proper.
The romance marketplace used to be fairly simple in the 1960s: no pre-marital sex, no graphic sex, romance ends in wedding bells, perhaps some use of the mystery or thriller template to surround the romance, absolutely no fantasy, science fiction, or paranormal elements (unless explained away at the end as a trick or something mundane misunderstood). Dark brooding thrillers in old dark houses were the hallmarks of the Gothic romance, which has had a small revival. Heroines did not do sex until after they were married to that man, and then always off stage.
In the 1970s, good girls could go bad in historical romances called bodice rippers, because sex was forced on them and after that they just couldn’t really be good again. Bodice rippers died out by the earliest 1980s: it’s ridiculous to use this term for historical romances now, or even for all of them back then. It only makes the user look hilariously out of touch. Some of these also had occult elements, like heroes who were working sorcerers, which many romance historians have missed, but guess what I have in my collection.
Today, romances broadly sub-catagorize by level of graphic sex (based on Phyllis Taylor Pianka)…
Sweet romances are like those of the 1960s, the sort you wouldn’t freak at your 12-year-old daughter reading. No sex, on-screen or off. Publishers: YA like Leisure’s Smooch, or inspirational romance publishers like Heartspell and Harlequin’s Steeple Hill.
Spicy romances can have sex off-screen: lots of heavy breathing, but the camera fades at the bedroom door.
Steamy romances are currently dominant: graphic love scenes, and not always in highly coded terms. Heavy euphemism is getting to be Old School. However, they are embedded in stories that may cover a great deal more. Publishers: Harlequin in most lines, Lovespell, Avon.
Erotic romances just take it to the farther level. They emphasize love scenes over all the rest of the story, and are willing to be unconventional: racially mixed couples, gay couples, triads, S&M, and more. Publishers: Ellora’s Cave (which coined the term Romantica™), Loose Id, Erotique, Harlequin Spice. The catalogs from the publishers may tell you more where your work belongs.
Romance is the single largest-selling genre, with now many sub-genres according to setting, drift toward another genre (thriller, science fiction, action/adventure), subject, or other elements.