surrogacy

Li Shuyi (MC) took a bullet for Bai Jing (ML) 3 years before the story begins. The two were in a physical relationship with each other at the time. But it was also a turbulent time because the ML's engagement was fixed. The MC (the stubborn man that he is), this was unnaceptable to him so he threatened the ML to break off the engagement. And his threat would be pretty damaging because he was the ML's business partner and right hand man. However, as the MC says later what would he have actually done. His only weakness is the ML. His reason for threatening was not just for himself but also because the girl whose engagement had been fixed with the ML wholeheartedly loved somebody else. So he wanted to help her out too. He knew it would be a completely empty marriage if the ML and she got married.

Anyway so because he takes the bullet aimed for the ML, Bai Jing feels guilty and breaks off the engagement and they decide to stay together. So, the MC thinks it's because of the guilt and not love. And fool ML thinks the same, he is staying because of the guilt. But there is an additional layer to Bai Jing's guilt. His guilt is so deep because he had planned an assassination too. He had planned to "take care" of the MC, he had even mentioned this to somebody else. Even though he says he did not assign anyone to carry it out but he definitely thought about it and would have even done it maybe, if the MC had not taken the bullet for him (we will never know).

The cruelty is in the fact that he wanted to kill him after the ML and MC had known each other for so long. It is the ruthlessness that he has been taught since childhood. Even the MC with a similar personality as his agrees that he would have done the same if somebody threatened him and told him what to do like he did to the ML. But it hurts because they had known each other for more than a decade by that point. Worked together, built the company together, been together.