The Dragon asnd the Pearl by Jeannie Lin
This sequel to Butterfly Swords is about Ling Suyin, the favored concubine of the late emperor, and Li Tao, a reknown general who served the late emperor, and who believes Suyin is conspiring with one of his enemies. I remembered Suyin from the previous book, but didn't remember Li Tao until reminded of his exact role in the plot.
This starts with the plot well under way, with Li Tao having abducted Suyin in hopes of learning of his enemies plans. While I am definitely not a fan of "in love with your kidnapper" plots (as in, "at all") this initially didn't bug me as I felt they'd respected each other for years despite not really knowing each other, and she was treated with respect and he didn't seem to intend her any harm and...well, there were actual sound (if ultimately misguided) political reasons behind it as opposed to using her for revenge/power/threats. Unfortunately (if unsurprisingly) it entered into "I'll let you go if you spend the night with me" and "trade sex for freedom" always falls into very dubious consent territory (and I was iffy even beyond that for the first time they had sex) even if the person being told to trade sex for their freedom had major hots for the other and wouldn't have hesitated to act on it in other situations. So a hard sideeye there.
That said, the political plot is very interesting and I found their relationship pretty interesting too, and even moreso than Butterfly Swords, it reminded me of a lot of more serious, historical wuxia I've seen, though I often thought the flashbacks to their individual pasts and rising to power in the court to be the most interesting parts.
The setting also makes a romance novel trope we all love to laugh at actually work.
Suyin was a virgin! Which I did have a good laugh over (the emperor was impotent after a battle wound and, to avoid even more political struggle over the throne since he couldn't father an heir, pretended to be obsessed with the then-teenaged Suyin so that it would be assumed that she couldn't conceive and that he'd get back to fathering heirs once someone else caught his eye) but while "virgin mistress/widow" is absurd in the usual European setting for most historical romance novels that it shows up in, it works here because the reason actually makes sense, and also because the nature of political marriages (both for the official wife and concubines) for the tang dynasty (and other historical eastern cultures) did make it possible, if not incredibly common, for an emperor/noble to not have sex with one of the various women basically sold to him for political bargains/favors. (As Li Tao points out, that wouldn't be the case with who Suyin supposedly was to the emperor, but the fact that it actually likely would have been the case if the emperor hadn't needed a cover lends credibility to the plot point.)