I can't not recommend Bookworm, even though it doesn't fit your criteria.
From the reader's library:
Yashiro-kun's Guide to Going Solo is the best of those that I've read. The romance is central, but hidden, like a submarine which will eventually surface. As I recall, it is just two volumes.
Young Lady Albert Is Courting Disaster is fairly standard, but good enough that I finished the series.
Culinary Chronicles of the Court Flower seemed good, but didn't quite click with me, so I haven't finished it.
Of the non-reader's library, Marielle Clarac stands out. It is intelligent and believable romance, and does not stretch out too much the main couple coming into accord. This is my strongest recommendation.
I've been enjoying In Another World with Household Spells which is under the J-Novel Heart imprint, but the MC is a child and it isn't until volume 6 (the latest) that she gets old enough to get any romantic feelings at all, and even now it is a very minor part of her thoughts.
Jeanette the Genius has a romance aspect (MC and her fiance are very much in love) but the story concentrates on business and politics.
The Troubles of Miss Nicola the Exorcist is pretty good, has romance, but it takes a back seat to the exorcism plots.
My Next Life as a Villainess: All Routes Lead to Doom! is excellent for the first three volumes, at which point its primary plot wraps up and it just drifts thereafter. MC is oblivious to the (bisexual) harem she is accidentally collecting, so this one depends on how you feel about romance-oblivious MCs.
In general, the "J-Novel Heart" imprint doesn't guarantee romance will be more than a minor side plot.
