Romance is in the air - and on the blog! As before, I am going to try to not repeat any of resources I listed before. Note that you can use many of them for a variety of genres.
There are so many romance book blogs! I will list a few here but if you are a fan or have a huge patron base for them, you might want to spend time searching for them.
Harlequin is one of the publishers even those who are unfamiliar with romance know. One of the most useful things on their site is what they call "favorite romance storylines" or what other people call tropes. They also talk about "miniseries" on their site which allow "readers to return to the same town, family or cast of characters to fall in love again and again!" There are non-Harlequin authors who do this. It would be a fun way to market your series fiction - call them a miniseries.
Smart Bitches, Trashy Books has been around for a long time. It includes a blog, book reviews, book suggestions, and a podcast. They cover romance news and what's trending along with being a great place to go for your next great romance read.
Dear Author is another long standing romance blog with reviews, new releases, recommendations, and essays. As with SBTB above, books outside romance are reviewed and pop culture like TV shows and movies are also reviewed and discussed.
WOC in Romance is a blog that promotes and highlights books by women of color. The section labeled Find Your Next Read has tropes, subgenres, and categories of romance fiction. Use this to help make your displays as inclusive as possible and find authors you may not be familiar with.
For queer romance, check out LGBTQ Reads. There is a section on the site devoted to romance with lists devoted to teen and adult romances with a wide variety of character identities and pairings. There are articles and upcoming titles. They also list books by region, historical romances by era, trope/archetype, and setting.
The Ripped Bodice is an independent bookstore specializing in romance. They produce The State of Racial Diversity in Romance Publishing Report. Besides news about upcoming releases there are also staff suggestions and book lists.
A Reddit user curated a map with all of the romance oriented bookstores in the US and Canada. Their sites have information about tropes, subgenres, archetypes, and what's hot in romance.
British romance author Evie Alexander has a list of 150 romance tropes on her website. Any of these can be used for a list, blog post, book display, bookmark...
Romance Writers of America is not without regular controversy but there are some useful pages on their site including a basic breakdown of the genre.
The Golden Crown Literary Society focuses on sapphic/women loving women literature including romance. Their awards page could be useful for learning more about this subgenre.
Romance.io is a blog with a unique book finder which you can use to find books with particular kinds of heroes, heroines, tropes, and more.