Why Is the Little Apprentice I Picked up so Sickly?

Single HeroineDouble Cleanliness Master Wenrun×Yandian Disciple When I picked her up in the ruins, she was covered in blood. She grabbed the corner of my clothes and asked if I would leave her. I said no. I taught her how to read, how to draw breath, and how to behave. Later, she grew taller and surpassed me in cultivation, and started to drive everyone away from me. Then she blocked me in the cave and said one sentence—— Master, you have taught me for nine years, but you have never taught me how to let go. Then you teach me now. I can't teach. Because I was locked up by her.