Reikoku Ou wa Hatsukoi ni Kuruu

Princess Sophia, whose birth sacrificed her mother's life, has lived a lifetime of oppression, having received an oracle of being a "Kingslayer" that will one day threaten the life of her father, the king. On the same day the new king of a neighboring kingdom comes to greet her, she hears of her stepmother's plans to assassinate her...

(Source: Mag Garden, translated)