Warning: This review will contain spoilers!!!

Plot: A woman falls in love with her boss at first sight.
For three years she works at his company, cherishing each moment they casually meet and interact, snapping and collecting pictures of him on the sly. (Not stalkery--just very cute). He, of course, is completely clueless to all of this to the point that...
....three and a half years later, he asks her help to "pursue" her best friend.
FL knows that her bff is in a relationship with someone else. Nonetheless, she seized the opportunity to get closer to the ML, so she agrees to "help" him pursue the bff. Using this excuse, the ML and FL begin spending time together, meeting and talking purportedly about the bff but eventually it reaches a point where they're almost like friends (despite him being her boss). Even after the bff gets married they still meet and interact.
The FL falls deeper and deeper until she decides to confess, whereupon the ML rejects her outright.
In his defence, her confession seems sudden, since he has no idea she'd had feelings for him for years. He just sees someone he knows as an employee and causal friend suddenly confess out of nowhere. When he asks her to explain why she likes him, our FL panics and lies, giving a very shallow response: "You're handsome and rich, of course I like you". The ML, who is the opposite of a playboy, naturally finds her response off-putting and tells her that they are not suitable.

The FL takes the rejection hard. But she accepts his decision and immediately begins taking steps to distance herself from the ML. As soon as she does, we can see the ML begin having doubts. From the start, her response ("handsome, money") strikes him as off, and out of character for the woman he's gotten to know over the past six months. But each time he tries approaching her again, she shuts him down hard. The FL is heartbroken and won't give an inch.

Now we enter our cat-and-mouse phase.
He does everything he can to pursue her, using work (offering to produce the movie for the book which the FL authored), proximity (he moves next-door to her), and support (financial and otherwise-putting his reputation and business on the line to ensure the development of her movie).

However, the issue is that he still has no idea that the FL has liked him for so long or how very deep her hurt is.
And she is not able to tell him. She can't open up and trust him.
So we go around in never-ending circles.
Many obstacles are thrown their way during this point, from online dating rumours, to a parent-pushed secondary love interest.

After a long (long, long, long!!) wait, the FL finally accepts that he truly does like her and they get together.
Once they get together it's a smooth walk down the aisle. Both of their families are happy and supportive. They live happily ever after.

My issue: The first half of the show built on chemistry, sexual tension, and heavy emotions. At one point I became annoyed with FL for putting off the ML for too long. But eventually we see her on-screen breakdown when he finds out that she's liked him for so long, and I forgive her. However, once they got together, the entire mood of them changed. She became less mature, more playful, and the sexual tension/chemistry seemed to vanish. We went from a heavy drama to a sweet romance--the transition was too abrupt and the mood shift was so extreme that I couldn't really connect the couple from part one of the show to the couple in part two of the show. This mood lasted up to the final episode. The final episode redeemed it. It was still playful and light, but the chemistry came back at least. Overall, I was satisfied with how it was wrapped up.

The secondary couple is the Director of the FL's movie and the ML's younger sister.
I'll say this: both characters are truly wonderful people.
The younger sister is cute, kind, and hard working.
The Director is dedicated, sweet, and also very kind.
In a sense, the younger sister who, by virtue of her age, always acted much younger and girlish than the FL, actually acted much more mature in her romance with the Director than the FL did in her own romance with the ML.
The chemistry between the younger sister and the director was wonderful.
I truly liked them together.
I loved seeing her gradually grow up and take control of her life. She made zero mistakes in her relationship with the director and I admire her so much for that. Since we'd seen her as a very young and cossetted girl, she'd have had ample opportunity to screw it all up, but she didn't. Truly, truly amazing of her.
As for the director, he admired her from the start, took his time, guided her as she entered his industry, supported her patiently, and confessed at the right time. Kudos to him for a job well done.
This couple was truly amazing to watch.

The music was fantastic!!!! The ost was one of the best I've heard.
The shooting was great.
The cast was wonderful.
I will definitely rewatch this show :)