If you enjoy these bite-sized costume dramas but trying to sort through the gems from the rubbish, A Familiar Stranger is among the best of the genre. Like My Decoy Bride, one of the main characters recognize the other from a past encounter, and while the circumstances that lead to the marriage are different, the FL also has a false identity when she marries the ML.
My Lethal Man is also a romantic suspense series, with a similar "mood", involving the lead couple trying to solve a family mystery/death.