I don't understand at all. What did Kincheol give up for Haesoo?? Both of them grew up in...

Getting older he hated the choice he made back then, he feels responsible he also feels she is responsible in a way, he is a very unhappy person, thats why he wants to keep a sort of a connection with her to make her feel bad and guilty because he hates himself for what he has become and her as well.

I mean, nothing of what became of his life is Na Haeso fault, she didn’t demanded anything - all of it was his decisions. But! As I understood the shady classmate, Mincheol could’ve had a rich girlfriend and have an easy life, he also was a good student and gave up college to hurry up and work so he could take Na Haeso out of her abusive household.

But what choice did he make? Not going to college to work?? But he didnt have money for college anyway. So why is she responsible for that? Why did she feel guilty everytime he took out a loan?? Man i don't understand

I understand him wanting to make her unhappy too but how is cheating going to help that?

Oo did I miss the part where he gave up college for her ? I need to reread

What I inferred was:
By moving & running away with Hae-soo, Mincheol sacrificed his chance to go to college. Thus, making it much much more difficult to graduate from poverty.

This is because:
- He used up a substantial chunk of his savings to buy a house
- to sustain their already meager lifestyle, he'll have to work constantly & would have little to no time to study
- the money he earns will be used to house & feed Hae-soo, instead of funding for his tuition

Moreover:
- his friend was hinting that if Mincheol became the boyfriend of the rich girl, she would have helped alleviate some of the financial burden

He basically sacrified his future just so Hae soo can run away faster from her abusive parent

Ahh i get it. Thank you

that makes more sense thanks for explaining