Hokay...
The coworker didn't have him up on sexual harassment/assault charges after (accidentally) ripping her shirt off, and offers herself as a marriage option... and he goes "Ha ha, good joke. Naw, I've got some options already, I think, maybe."
Oblivious.
Then again, Min-Eul did list stupid and dense, or words to those effect, as part of the characteristics she wanted when in a potential date when she was actually describing him.
And, after finally realizing that she was interested in him, and had been for years, and boinking her, he doesn't consider her an actual candidate for marriage, but merely someone who would go along with being a fake girlfriend.
WTF do these women see in him, anyway?
Yes, at heart, he's a nice enough guy, but man oh man, he is so f-ing clueless!
And very non-motivated about anything in his life.
The coworker started at the same time as him, and is now higher in the hierarchy... in Korea.
My understanding is that the glass ceiling is much thicker here and more opaque there.
He himself acknowledges that it's because he isn't putting out the effort and she is that she's ahead of him in advancement.
And, it's that he hasn't done anything to improve his life that has led to the threat of being disowned.
If this doesn't motivate him to move forward with his life... not fake it, like he's setting out to do, but really change his life around, yeah, I can understand where they are coming from.
Because, we haven't been shown anything that indicates that he isn't capable of doing far more with himself, he's just been content to drift through life.
It's not like he has a disability of some sort. You recognize those and work with them in regard to expectations.
But that doesn't appear to be what's going on.
His little sister... may not be a brocon after all.
What will her reaction be when she catches on to what's up?
Is she above using him to get access to Min-Eul?
Just what has the author planned for us next?