Romances, especially category romances, are unfairly characterized as formulaic. Sure, boy meets girl, boy loses girl, boy wins back girl, they live happily ever after. Of course they do -- that's what makes a book a romance novel. A mystery wouldn't be a mystery if there wasn't a puzzle to solve, and a science fictin novel wouldn't be science fiction if it didn't take place in a different universe/time/space.
One place that category romances do have a formula is in word count. The books are published as series, so all the titles in a particular line, such as Harlequin Romantic Suspense, are roughly the same length. But to people who point that out as a negative, I'd just like to say this: try to write a book that includes a romance and a suspense plot and do it all so the reader is totally satisfied when s/he finishes and within a proscribed length.
It ain't easy.
With an unlimited word count, you can meander your way to the end (if your editor will let you, and if she will, the reader probably won't, unless your writing is so lyrical that they don't care you're meandering). But when you have limited words to tell your story, every one has to count.
It's an art.