@Ryrie I am saying partly, because from their convo it is clear it's not only that, I think you are oversimplifying it, it's more complex than just jealousy. After all she rejected him, so it's not like she's head over heels for him. It's also pretty obvious she wants to keep him on a leash and him being in a relationship will ruin these plans. She's well aware that if he were to start a relationship with somebody the chances of him remaining that desperate for her are slim, the other reason is obviously to confirm his 'loyalty' to her. There's also the part where it is flattering for her to have men running after her - boosts her self confidence and reaffirms her societal value. And from her position and social perceived 'value' she's certainly used to men running after her. I would agree that she probably feels entitled to his affection even if she's not showing it too explicitly, however the MC confirms that she's right to feel so. He didn't have to refuse to answer, that would have been equally as stupid unless he planned to cut all ties with her. He could have simply left out the less flattering parts. As it stands he told her that he has no self respect, no self confidence, and no spine, so not only is he giving her the green light to lead him by the nose, but this is also counterproductive to his goal of starting a relationship with her. So not only is he pathetic, but he's stupid enough to let others know so that they would take advantage of him. Being a harmless idiot is not a plus, as much as manga like to make it out to be.
@HOOfan_1 Reread the chapter if you've already forgotten it. She invited him in a manner where it was clear it's not work (otherwise she wouldn't have had to secretly write messages on her screen and pretend she's talking about something else at work). The fact that he didn't say anything for 5 years, regardless of whether it was because he's an underling, tells her more than enough about his confidence, cowardice, and his conviction. If that is enough to deter him from courting her for 5 years, then it's obvious he's not that hot for her coupled with the fact that he's a wuss. Not a great combination to show off if you want to impress a prospective partner. If he managed to confess only under the influence of alcohol that's even worse from her perspective.
All in all, I really like how the author went about this, regardless of whether it was intentional. Since it's not (entirely) a mental masturbatory plot, and the MC's qualities are actually put into question, something you don't see often in manga.