The Villainess and the Demon Knight (Light Novel) Vol. 3 -

Since being reincarnated as a villainess in an otome game, Cecelia has been a marquis's daughter, a concubine, and now the fiancée of Lucas, the second prince and hero of the kingdom! After slaying an ancient dragon, Lucas whisks his beloved Cecelia to the royal castle to shower her with his insatiable affections. But the couple can't rest easy just yet. The queen has other plans for Lucas: she wants him to marry Lady Viviana, a noblewoman of royal blood from the neighboring kingdom. And if that wasn't enough to worry about, a shadowy figure seems to be targeting Cecelia...