Because he actually had a soft spot for her.
Accurately speaking, from the moment he decided to steal the child, he always had a thought deep down in his heart: "Would she be devastated if I stole the child?"
So even though things went according to plan, he never received the joy he imagined he would feel after successfully getting revenge.
Just like now. Cheng Weiguo's daughter was begging him in a manner as tragic as Lili's death. He should've mercilessly told her she could quit dreaming about seeing their son. However, as he stared at her, he felt himself repressing the urge to say that he actually really, really wanted to agree to do it.
She was Cheng Weiguo's daughter! Cheng Weiguo, that shameless old man! The worthless piece of sh*t who hid behind his prestigious status as a college professor. He never let anyone go, not even a young woman!