Vis, Mon Amour
An ordinary worker falls asleep during the height of the book she's reading, and finds herself awake surrounded by panicking people. Unfazed, her demeanor got cut short when a wrinkly hand reached out to hers. She turned to the owner and saw an old man, looking at her lovingly as he kissed her dainty hand.
"My Astrea,"
Turns out, she's their supposed princess, and she just awoke from death. What a convincing plot, right? Surely it was all just a dream; not that she was complaining. If it was a dream, it's just about time 'til her alarm goes off and wakes her.
News flash! It's not a dream.
Finding out that she really has been transported into the body of the villainess of her favorite book, the protagonist tries to find a way to go back, to no avail. Until her father- her body's father, tells her she's betrothed to the fearsome war veteran Duke. Finding it useless to stop it, she accepted and began to live her life as the villainess and wife of the infamous, ugly, disfigured and evil duke.
Until she finds out one day that her groom was not only not evil, she wasn't a husband, either.