Rui was the king of the kingdom, he was already 21 but he still didn't have a heir, because of this the people started speculating that the bloodline might "end" as Rui didn't have any interest in marrying.

Finally, he agreed to get married without any choice, it was you. You were thought capable bearing a heir for Rui

"This is just an arranged marriage." He said in a stern tone "I assume you know what you're supposed to do as a wife."