Damn. I just had another thought. In the next chapter, when Han Juwon
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has sex with a naked Lee Seodan in front of the apartment windows for all to see, it's like him staking his claim on Lee Seodan and saying to the world, "See, he's mine. You can't have him. He belongs to me." I think Han Juwon wishes they could go public with their relationship but as a boss/subordinate, but they obviously can't, so he kind of takes it out on Lee Seodan by having almost-public sex.
Lee Seodan is cute, affable, easy-going and his colleagues tend to be playful around him which pisses Han Juwon off no end. Every time someone interacts with Lee Seodan in a playful sort of way, Han Juwon flies off the handle and probably wants to scream, 'He's mine, you can't touch him, only I can touch him!'

Han Juwon can't separate work from his personal life. His reaction to Lee Seodan's report was an over-reaction and he admits it in the next chapter. The report may have been flawed, but he over-reacted because...
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he felt like Manager Kim was being too touchy-feely with Leo Seodan by tapping him on the shoulder and being chummy with him. So Han Juwon is feeling possessive and jealous. He suggests moving Leo Seodan's next to his, so he can keep a better eye on him and keep other's hands off him. Leo Seodan thinks his reaction is cute and funny.
Leo Seodan didn't think Manager Kim was crossing a line, but asks how is he meant to stop a shoulder tap? Han Juwon sees his point, but still feels frustrated. Remember, he once said that he had the impulse to kill anyone who paid attention to Leo Seodan.
In the next chapter, he forces a naked Leo Seodan to have sex with him in front of the apartment windows and then mischievously bites him on the same shoulder that Manager Kim tapped him on. If that's not an over-reaction to a shoulder tap I don't know what is!