I haven't watched that, but the trailer reminds me of these dramas:
1. Cunning Single Lady | FL divorced the ML when they were younger. Now, he's the CEO of a successful company while she is struggling to make ends meet. She attempt to get hired at his company and, though unwilling at first, ML yields and she gets the job. Don't judge this drama by the first episodes. FL is portrayed very materialistic at the beginning but you will soon realize she had an understandable reason for leaving him. She is also hard working and smart. The relationship between the leads starts of a bit rocky and hostile, but it changes at a good/natural pace.
2. She was Pretty | I have some issues with this one, but overall it was enjoyable. FL is forcefully moved to the department led by her childhood friend and first love (who doesn't recognize her). He is very demanding (impatient and cold) towards her in relation to the workplace and she struggles to keep up with his insane pace. But she is hardworking and ends up winning his heart.
3. Jelousy Incarnate | FL wants to become an anchor, ML gets annoyed with her and tries to keep her at a distance. She obliviously keeps getting close to him until he starts to value her. This one has a looooong love triangle towards the second half.
4. Master's Sun | FL forces her way into ML's life because he is the only one that can keep her from seeing ghosts. She ends up getting a job at his hotel. At first he doesn't like it, but then he sees how hard she is working and accepts it. Later on they strike a deal and he gives her her own office. This one is really good.
