Your Highness, I'm That Princess of the Fallen Kingdom

If not for that war, I would still be the carefree Princess of Lingyue. Sadly, the Princess of Lingyue died in that war. I came alone to the enemy kingdom, carefully plotting every step of the way until I made their most noble prince fall in love with me... Then, just as he trusts and cherishes me with all his heart, I kill his father right before his eyes, to avenge the Lingyue royal family.