Well, this is not just genre, but sort of a hybrid genre.
Patricia Ryan just added her "A Gilded Age Mystery" series (originally published under the P.B. Ryan pseudonym). There as six books - a mystery series set in 1860s Boston. The stories center around a young Irish governess, Nell Sweeney, who gets pulled into various murder investigations.
There's a romantic interest, but it's very slow going and doesn't overtake the mystery stories. He is the opium-addicted son of the people Nell works for (and the father of the child she takes care of).
I very much enjoyed these books.
If you're at all interested, the first book in the series was just
reviewed at a blog I like to visit (it's how I found out the books were released at Smashwords). I'd read them in DT format, but am gladly replacing those with nicely priced ebook copies.