This is my least favorite part of this story.
She wanted to become the young leader herself, it was her driving motivation. And she was better than everyone in her generation except the MC.
Then she gets chosen as the Divine Maiden. Her martial arts are now useless, a Divine Maiden doesn't need any and has no occasion to use any. If the MC doesn't accept her, she'll be forced to be alone the rest of her life.
That's a bitter fate for a woman with so much ability and who put in so much effort. To be reduced to an isolated fire tending concubine awaiting the condescension of the MC. No matter how honorable a position it is, how miserable.