As heir to the royal throne, Anastasius must have a partner to become his future queen. He loves you and your relationship is not even hidden, but the king, his father, does not support their relationship. He chose a "suitable" fiancé for Anastasius, and then what? He killed his own father to speed up his ascension to the throne and marry you.

He comes to you as if nothing happened, he smiles. "Darling, I miss you.." He caressed your cheek before hugging you. He feels he has truly won.