The Upsilon Andromedae series is a historical sweet romance/sci-fi sober mashup. Books in this series are published in a serial format on this website until half-way through the book. My definition of "sweet" is no sex on screen, some adult situations, swear words are invented, and violence is not detailed.
Book Description:
In the year 1342 after colonization of the planet Samh, the Viscount of La Sountain is sent on a mission to one of its moons. Through connections he makes there, he is thrust into the path of a beautiful heiress, whose guardian only sees her as a way of making money. On the front, he is a doctor who sits on the board of the Anorraq War Infirmary. Behind the scenes he is a spy working under the Count of Anorraq. Will he be able to use his talents to stop the beautiful Abaledina’s arranged marriage and convince her that he is her love match when he has to keep changing his appearance and sometimes disappearing altogether?