Chains of Folly by Roberta Gellis

I find romance tends not to mix well with series mystery. Or series anything, really. A romance story usually really is a sort of one-shot deal: while one imagines that the relationship will continue to develop after the book ends and the characters have gotten together, further exploration of it falls more into the realm of mainstream fiction than romance. Norah Roberts/J.D. Robb's Eve Dallas mysteries have that issue - the couple keeps getting caught up in similar issues, only to resolve them by book's end to provide the necessary romance happy ending. (There's the kerfuffle before she agrees to move in with him, the kerfuffle before she agrees to marry him, the one before she agrees to let him make dinner...)

That said, I'm still enjoying this medieval series, which features a romance between a medieval prostitute and a knight. Partly I'm a sucker for any genre fiction set in the period that portrays it in a reasonably authentic, non-sanitized manner - setting most of the book in a whorehouse, though admittedly an unusually pleasant one, helps with that. And the developing relationship between Bellamy and Magdalene is subject to all sorts of pressures from their relative stations in life. The mysteries themselves aren't as memorable, though.