You are right. On the day of marriage ceremony, she tries to hypnotize Ryan and marry him. But her spell brakes by Aisha and everyone looks at her in disdain. That's when Arundi comes and open the gates by killing the king. He tries to kill everyone there. He tortures Robina too.
But Aisha finishes him off and leave the country with her husband. Never returns.
Robina's best friend marries the prince and become the queen.
Prince is still scared of blonde girls. Robina's who body is injured. No one cares for her. She became a maid and everyone hates her.
Her family regrets not loving Aisha but she cut ties with them. The young brother grow up and go to her country.
He saw how much his sister is loved by the people. He met his nephew and niece. His sister notices him and welcome him warmly.
The end.

K so idk if this is true but I heard that when Aisha and Ryan goes back to Robina, her pick me girl sister bumped into Ryan without knowing he's the grand Duke and fell in love, then she'll ask her parents and Aisha to divorce Ryan the moment she knew he was the grand duke