Review Detail of Oppai_San in I am Over Powered in Douluo Dalu [Haitus]

I was liking this story at first, but as the story continued it just became really bad at character progression and development. First off, with the way it is structured, it feels like the author just decided to make Zhuqing the romantic interest for the story after already writing the main characters backstory. The way he tries to introduce Zhuqing as a romantic interest and force him to train her really bothers me as before this he is depicted as a stone cold killer, but when Zhuqing threatens him he is easily coddled into saying yes without addressing the fact that he has her life in his hands and doesn't need to bend to her will, and then he also starts teaching her his clan moves and kata, which is insanely absurd considering his supposed background and the way his personality was built up to that point. My point is there was no character progression, it was just an immediate switch from stone cold killer to him having a schoolyard crush on someone that is significantly younger than him mentally. Just giving some constructive criticism, respond in the replies if you have anything you want to agree or disagree with me on.