I'm the Villainess, So I'm Taming the Final Boss Akuyaku Reijou nano de Last Boss wo Kattemimashita English Subbed

Aileen Lauren d’Autriche’s wedding plans have been suddenly canceled— by her own fiancé! The shock of this jolted her into remembering she’s been reincarnated in an otome game as the villainess. As she recalls, her fate is one of doom, but maybe she can avoid it by marrying the final boss, the Demon King Claude. Her new game plan— seduce the Demon King and live happily ever after.

(Source: Crunchyroll)