EXPLANATION - brace yourselves cause it’s a detailed one, I can’t keep it short…

I had such a hard time making sense of all of this, hope I can help you all clarify some things.

Let’s start off from some background on Seop’s character in the story: he was pressured by his father throughout his life to do his best and always be the best to the point of developing panic attacks. But then one day his cousin whom the family didn’t know existed appeared and Iseop gained a rival in succession. Iseop’s dad made some mistake and because of that mistake his cousin was the one who gained control of the company and became the vice-president. For Iseop it was like all of his life efforts were in vain and he wasn’t even the one who did anything wrong. (that’s why he kinda lost his drive and became lazy until the FL awoke the competitive passion in him again). He also does feel guilt about the fact that FL was always better than him but she ended up as just his secretary because of nepotism. Like, he regrets they don’t have the same standing and is afraid to pursue her from the position of power cause he thinks she treats him as a responsibility that she cannot defy.

Now onto the boring part:

The first mention of that “Resort project” is in the earlier chapters. It’s insignificant what are the details of that project, it’s just one of the things he was appointed to take care of.
Now, “m&a” that is mentioned in this chapter isn’t some company or anything, it’s a team on the TK company (the one they are all working at if you didn’t care to remember lol). M&A is a buissness slang abbreviation so let me explain what they do. If your brain can’t comprehend buisness talk then just skip the next part lol

M&A means merging and acquisition. It’s a strategy to expand a company (as - buying smaller companies) and those are like two different ways in which you can do that. So I’m assuming that the team was responsible for deciding how to proceed with management and the legal aspects of buying a smaller company into theirs. It’s kinda hard to understand so I will try to make it easier. It’s like the difference between buying a piece or pieces of something and trying to fit it into your own structure VS buying a whole structure and adding it to your own (in its original shape).
So acqusition = buying pieces - you simply pay a company and buy their assets, you are free to do whatever you want with it but it “loses structure” - so for example you have to rehire all the employees !! (important in this case)
Merging = buying structure - more legalized, you need state fillings, all of the parties involved need to agree but the employees keep their job.

Their m&a team did an oopsie and used acquisition instead of merging in this particular case. FL explained it was because they wanted to save the effort. So if you skipped the paragraph above - all the employees of the smaller company they bought were fired and there were probably some issues with accounting and such.
1) That’s why so many people were protesting in front of company - their companies were supposed to be joined but they prob lost their jobs or sth and now they blame the director in charge (Seop) and are demanding “employee succession” - change of director for someone who is qualified instead of a family member.
2. During the talk with her creepy bestie blamed Iseop for something like - M&A committed some creative accounting and fraud. When FL tried to defend him and explained it was the cousin’s who handled that case he was like “ye, but who benefited?”.
So everyone blames Iseop even though he didn’t know anything about it.

Now putting the pieces together - why Iseop got so mad. First of all, everyone in front of that building wants him fired and blames him even though it wasn’t his mistake. Which is kind of similar case to that from his past - when his dad made a mistake and all of his efforts went to shit. Secondly, he got so emotional because as he said “he also cares about this company and sacrificed his life for it but he still has to clean up someone else’s mess”. And thirdly he told the FL to just be moved somewhere else and give up on being his secretary because he was yet again being accused of being not-deserving of his position. Like, they wanted him fired and someone actually capable to replace him. So he felt the guilt again.

BUT the FL told him that the reason why he was able to keep his position in the first place after what his dad did was because the employees know that he deserves it. (the ones protesting are from another company) And that for her too it is an honour to work for him. So yeah, she kinda reassured him, perfectly eased his worries and motivated him to resolve this instead of agreeing to be the victim again.