Suspending disbelief is difficult when the CEO is also allowed by the police to act as a detective and go along with them and, of course finding, analyzing critical data.
However, the biggest problem with this show is a lack of understanding of relationships. You can't build a relationship on an abusive, possessive basis. Nor can someone, in this case the CEO, fundamentally change his personality so quickly.
SPOILER:
The CEO's family owns a hospital so he is able to fake medical records indicating the objective of his desire (definitely not love) has leukemia and he is the only compatible donor.
Then, he gives her many rules to obey and, at one point, actually holds her captive. He treats her as a possession.
How in the world can a loving relationship be built on these fundamental misunderstandings of the difference between love and lust? Then we are to believe he quickly controls these destructive tendencies and real love comes out of this?
I couldn't suspend enough disbelief in the basis of this show and I think I am being generous with a 6 rating. While not everything is awful, I also found the bad guy, someone worse than the protagonist, to be a caricature of evil with no redeeming qualities. A bit too extreme in today's entertainment where I expect most characters to be a mix of good and bad.