A year and many kdramas later I finally got to write a review about this drama - imho, it's still one of the best rom-com kdramas out there, very underrated. It flew under the radar when it aired due to lack of proper promotion and because there were other overhyped and frankly overrated dramas airing at around that time, like A Business Proposal, for example.

Yes, on the surface it has your typical boss and secretary premise, but the plot itself is far from being generic, it's actually quite unpredictable. The first giveaway is in the premise itself - FL learns that she doesn't have much time left to live and ML is in danger of being murdered by somebody (don't worry about it being scary sounding though, nobody's actually going to die and it has a very happy ending). As the episodes unfold, this drama breaks away from the stereotypes and cliches you'd expect, and turns them on their heads in a creative and hilarious fashion.
This drama doesn't rush character exposition, but doses it expertly throughout the episodes. It has a rather slow start to give time for characters introduction and to show the crux of their problems. So after the first few heavy episodes you can't really say anything definitive as to where this is going. But after everything is established and the plot starts moving in full swing you'll see that this is a rom-com at its finest, with lots of unpredictable situations and funny moments that are very entertaining to watch. And while it's not some brainy mystery thriller that the audience has to solve, there are elements of that here as well. This drama mixes familiar tropes in a rather unpredictable and surprisingly balanced way, and doesn't falter or fall off until the very end. The narrative is strong and well thought out. And it rewards viewers who paid attention by meaningfully referencing and shedding new light on earlier events and dialogues in later episodes.

The two biggest points of this drama are:
- a strong overall message of redemption and forgiveness;
- an absolutely fantastic character development.

ML initially comes off as cold hearted, arrogant jerk with nasty temper and terrifying boss aura, who bullies his secretaries for nothing (for which FL makes him pay for later). But later it turns out that he's just a lonely, miserable guy who was backstabbed and abandoned too many times throughout his whole life. With such bad attitude and due to complicated past with some of the characters, ML becomes a target of ire of many antagonists, who gang up on ML to ruin and even kill him. And there were a lot of them for various reasons - revenge, competitor elimination, jealousy, financial problems, etc. Some were justified, but as the plot unfolds it is revealed that mostly he was made a scapegoat for other people's problems. This drama's doing well at showcasing that people generally are flawed, selfish, egotistic and like to put the blame on someone else, instead of themselves, because it's easier. But it was all done on purpose for ML's and their character development, as most of these characters in the end will come to realize that they were in the wrong and will make amends. So even though ML comes off first as a real cold bastard, the drama does a good job at portraying the why of it and his eventual path to redemption.

FL initially comes off as unassuming, timid, hard working girl, with presence that of a wind in ML's company. But after she learns the dire news of her imminent death due to health issues, she decides to put the blame on ML for being a giant stress generator source for her for over a year, which reasonably could have exacerbated her illness. With nothing to lose, she decides to go out with a bang and to take revenge on ML before she dies. To help FL with this endeavor fate conviniently throws her a great opportunity, enabled by one big mistake made by ML. While being hospitalized after an attempt on his life was made on a fateful day X, ML decides to fake his amnesia to expose the suspects. FL uses this to her advantage and pretends to be his fiancee to gain full access to his body, so to speak. And from here on out hilarity ensues as she starts implementing her revenge in an unfazed, zany fashion and ML has no choice but to suffer through all of it, lest his cover is blown.

The first half of the drama is focused more on FL and her inner turmoil. I really liked FL's somber, self-reflecting scenes in the first seven episodes, as well as ML's gradual shift of attitude towards her starting from around episode 6, as they start spending a lot of time together. And though the later part of the drama is focused more on ML's redemption arc, the writers didn't forget about FL in later episodes either. Though her main problem is effectively resolved in the first half of the show and she turns back to her kind and nice self, she gains a newfound courage and profound realization how she should be living her life from now on, and starts pursuing her dreams in earnest. This all helps immensely to resolve ML's problems in the second part, as she's there to support him and lead him in the right direction. This plot division seems very deliberate, as one plot point leads to the resolution of another. It couldn't have happened in parallel if FL was still dealing with her problem till the very end and continued having crazy bouts with ML, however hilarious they were.

Once the leads clear their misunderstandings, stop hating each other and find themselves falling for each other, they are all in for one another. No dumb break-ups, time skips or LDR. It is very sweet.
That this drama basically has no love triangles is a big plus for me as well. The leads have eyes only for each other here. ML's delulu ex, with zero second chances given, ends up being just another one of the antagonists.

So all in all, I liked how the show gradually showed their character growth and how competently all the plot points led to a satisfying conclusion, with a moral to the story even. Not every drama out there can boast the same.
Maybe the list of people having a grudge against ML could have been shorter, especially considering that most of them were not out there to get him for his nasty demeanor, but for their own selfish reasons. But I think it was done deliberately for that explosive dramatic culmination in the later episodes.

So, a great drama overall, definitely worth the watch. Starts a bit slow in the first few episodes, but gets really good later and doesn't let go until the very end. Nothing is rushed, for once, and the ending is very satisfying. The first half of the show where the leads were at each other's throats was absolutely hilarious, with pinnacle pillow fight being simply iconic. And the second half of the show was full of surprising revelations and sweet moments.
I think ML's actor did a formidable job here at playing a competent, but terrifying boss on the outside and lonely, betrayed guy on the inside. I absolutely loved his performance. In many rom-coms of this type actors can't pull off a proper boss role, they often turn up either too soft or too dumb to be convincing. But here he practically had that aura about him.
One might say that everything that happened to ML in this drama was accumulated bad karma, but he came out of it a better man in the end. And it's funny that it was the timid and introverted FL of all people, who mustered her courage due to her life changing circumstance and stopped putting up with his scumbaggery, that was the catalyst of ML's change for the better. I wasn't a fan of FL's actress before, but she really grew on me here.

Not giving this drama a perfect score only because some side characters in this drama were pretty useless/underutilized and more often than not were wasting screen time. For example, the gossiping ex-secretary club or goofy FL's brother and girl friend couple. And also, be prepared for good old staple of all contemporary kdramas - PPLs in your face.