Romance novels are formulaic, which doesn’t mean they can’t be interesting, charming or insightful. The basic formula is boy meets girl, boy loses girl, boy gets girl. A variation might be: boy previously dumped girl, now girl hates boy, boy works to get girl back. The reader knows at the beginning of a romance novel who the boy and girl are and that they’ll get together by the end of the story. It’s just a matter of how they get there.
Within the formula, there are recurring themes. One is the unexpected baby or child. If romance novels were true life, about 10,000 ranchers, and quite a few members of the British peerage, have/had children they didn’t know they conceived. For British or Scottish stories, there’s always the unexpected elevation to the peerage. It’s usually a rake, a soldier, or a guy who was raised in the slums. If it happens to a woman, she was a wallflower, country bumpkin or a girl who was raised in the slums.
Then you have the convenient marriage that turns to love. These unions happen in the English and Scottish stories but also in historical westerns, where you’ll find not just mail-order arrangements but matches based on business or other concerns. My least favorite themes are the ones that involve an old flame returning to town. Yawn! I like fresh blood, not recycled romances.
And within the mail-order bride genre are subsets of themes. There’s the mail-order bride who arrives at her destination to discover her groom is dead or AWOL. And the mail-order bride who’s not who she says she is. Most likely she’s a saloon girl who took the identity of a mail-order bride who died. And the sister/friend/cousin who comes in the mail-order bride’s place because the original intended bride is an awful person who has run off with another man.
So there are only so many stories to tell. Romance novels are indeed formulaic, but how you tell the story is what will make all the difference. Add your own twists and turns in the voice that is uniquely yours.