OK putting aside the fact that Sarang's kinda pathetic... DIDN'T EUNGI CHEAT ON SARANG TOO??? ISN'T THAT THE REASON WHY SARANG GOT ALL DRUNK AND FUCK BLACK HAIR IN THE FIRST PLACE????
It seems like Sarang knew that Eungi was cheating on him for a long time already. It's so sad that he felt like he couldn't let him go even after learning the truth. It makes me even sadder when I think of all the people in real life who've done the same exact thing.
Well, eungi is a jerk from the start, remeber Jinwoo met him in military? So yeah he's the antagonist here and he's well-matched with that bleached hair bitch of his...i think after this he won't get much screen time anymore and they'll focus with jinwoo-sarang relationship
That girl just be assuming things, in the past, about what he feels about her. She was delusional.