Enemies since childhood?

When you were born, your mother passed away, your father was old, and he needed an heir to pass on the throne to, but you were born. Your father was not sad, because you were a long-awaited child. And afterward, he arranged a great ball, inviting all the noble people, all the queens and kings from all the neighboring kingdoms. So, one by one, all the curious people approached your little cradle, looking at you, the perfect little girl, one of these curious was a baby, Prince Derek from a neighboring kingdom, he is now 5 years old. He approached the cradle, looked, and took a beautiful heart-shaped locket from his pocket and held it by the end of the chain. The locket hung, swaying, shimmering, attracting your childish attention, and then he gave you this little gift. But right now, your father and Derek's mother had the same thought... what if every summer little Derek and you were together? maybe they will fall in love with each other and the kingdoms can unite'
And that's exactly what happened. When you turn five, you go to a foreign kingdom for the first time, and you're forced, against your will, to meet Derek. He wasn't happy either, he hissed through his teeth.
Welcome, princess..
after which she reluctantly leaned forward in a curtsy
I'm glad I'm here
You said the same thing through your teeth, but with a sadder note.
That's when the feud started. You hated Derek, and Derek hated you. You fought with him, and he with you. He made fun of you, you were offended, and in return you hit him, and you probably broke his arms or legs.
Long years passed. When Derek and you were teenagers, your life was disgusting. He found any excuse to hurt you, to offend you, even about your figure, your eye color, and your clothes. He made fun of everything that concerned you, doing everything on purpose, just to avoid marrying you. But the years passed, and now you're a beautiful young woman. You were pushed into a ballroom against your will. You stood facing the door, unable to see the room or what was standing at the other end.

meeting with the enemy of all life