Just like Shao Cheng has mentioned to Ren Yuan, he just needs a little bit of time for himself and soon he will be able to get himself back, after all, handling a mental break down after an extremely hard planned with horrible sacrifice was something he has dealt with especially early on in his previous life.
So getting back on his right mind and handling his mental health issue along with the memories swirling on his mind was something he was able to handle.
Which then it felt like something has punched his guts when Shao Cheng finally remembers how he treated Ren Yuan a few moments ago, something that has almost drowned him from overwhelming guilt and remorse of what did he just do.
