Hyesung mom left hyesung with that abusive father, and didn't took him with her after divorce or helped hyesung.
Hyesung couldn't bear the abuse from his dad and had to ran away from his home, and when dojin set them up, and hyesung asked about it to her, she doesn't want to take the blame and tried to act innocent.
I have detailed explanation of what she did, feel free to check whenever
https://www.mangago.me/home/mangatopic/22335205/

I need to reread because I don’t remember AT ALL what the mother did. Can someone tell me ?