The fact that I talked with guys who told me that men can cheat without feeling anything (sex is just sex), and Mincheol is exactly it. He didn't consider what he was doing as cheating because lust is lust and it would end eventually, and he would come back to Na Haesoo. In the beggining of their relationship she really was helpless without him and he took for himself to protect her, but eventually took for granted all her love and no matter what he did she wouldn't do anything because, again, she was helpless without him. Then a girl who is young, pretty and cute appears and is lusting for him, what does he do? Sex of course, sex is just sex. He disregards it so much that in all of his panels and his monologues, he NEVER considers true divorce (they just divorced on paper because of the debt). So yes, maybe he was a nice guy before, but he became one of those guys who considers loyalty an emotional, not carnal thing.
The fact that I talked with guys who told me that men can cheat without feeling anything (sex is just sex), and Mincheol is exactly it. He didn't consider what he was doing as cheating because lust is lust and it would end eventually, and he would come back to Na Haesoo. In the beggining of their relationship she really was helpless without him and he took for himself to protect her, but eventually took for granted all her love and no matter what he did she wouldn't do anything because, again, she was helpless without him. Then a girl who is young, pretty and cute appears and is lusting for him, what does he do? Sex of course, sex is just sex. He disregards it so much that in all of his panels and his monologues, he NEVER considers true divorce (they just divorced on paper because of the debt). So yes, maybe he was a nice guy before, but he became one of those guys who considers loyalty an emotional, not carnal thing.