This drama has a promising premise, in my opinion. I think this would be better if it's wrapped up in 12 episodes, but it chooses to be a 24 episodes drama.
I'm from the psychology area, I can say the writer knows NOTHING about this kind of disorder, and have no interest in psychology either. If I rant about the psychology area, the wrong approach that the FL use to cure him, how he can casually change from Ming Dynasty to the present time, why can't the FL even be able to overcome her trauma (she's a therapist for GOD shake), etc, I'll end up writing a ranting novel. I'll write some basics which annoyed me the most.

First of all, a therapist will definitely lose their license if they're having a romantic relationship with their patients. Big NO.

This is quoted from the drama's page "Involved in a car accident at a young age, he developed a strange neurosis that worsened with time. Believing he is the Ming Dynasty’s Emperor Jianwen , Xuan Wen cares only for the prosperity of his imaginary empire." Judging from that statement, the ML's suffering from SEVERE Delusional disorders, this disorder will never occur due to an accident. And as his condition in the drama, this will take years.
Why this annoyed me the most, is because in the drama he has a psychiatrist (the FL's boss) who diagnosed ML with the disorder. Not to mention the FL and the second FL are both therapists... so...basically, he can easily trick 3 licensed psychologists??? Something that even the uncle the FL's brother can easily figure out but somehow these 3 psychologists can't?? Is the writer really think we are that idiot? We can diagnose a psychopath, there's no way a mere CEO can easily trick us. We can spot people who really need our help VS a liar in less than 30 minutes interview

I think it will be more logical if after the accident the ML found out someone wants to kill him. In his effort to find the perpetrator, he pretends that he's suffering from delusional disorder and hire a therapist to join and support his plot so that it looks more believable and people around him believe that he is not in a normal mental state.
This also means that the ML and FL can have a romantic relationship since he is not her patient. What's the point of tricking her anyway?

What can I say, the writer is just too lazy to study.

I can enjoy watching it without skipping any parts just until ep 7, but then, it is just too boring. Too many unnecessary sweet scenes of the main couple. If you watch until ep 8 and jump to ep 16, you really won't miss anything.

This drama is totally stress-free. I can't find a cunningly devilish villain in it. I also like how she can calmly face her heartbreaking. Overall, messy storyline with zero knowledge of the area it tried to raise about, but still worth watching.