Disagreed. So what if this is a overused plot setting for hundreds of BL series? it still doesn't justifies anything. "Let's try dating casually" is not something that you should propose to a random straight junior that you secretly fancy. Going as far as to kiss him without his consent when you're far from having a close relationship with him. That was just creepy. "Sunbae never tried to force him" the relationship itself was a result of a forceful decision carefully placed upon Ik-su. Ik-su was naive and dumb to let that happen but the sunbae was so perceptive and knew better and yet he clung to Ik-su and their almost non-existent relationship. His actions weren't highlighted strongly infront of our eyes because unlike any
other violent, harasser kind of guy, he was calm and quiet in nature so it felt harmless, plus the author didn't bring much colour to his character so there wasn't anything important about him anyways. Hence, he became a pitiful second "love interest" whereas in reality, he never stood a chance and this was just all just a dumb move from him. Also, saying that his only crime was him not being the main love interest is hilarious because he was being nothing but a third wheel throughout the story. Bro was just NOT into him
Actually he did kind of try to force him. At the beginning of chapter 7 he has Ik-Su pinned down and even though he says no multiple times, the dude rip his shirt off, takes his pants off and insists that "they've come this far" and "there's no way out." Ik-Su has to forcibly kick him off the bed after saying no and saying he has to leave doesn't do anything. So. Even if he wasn't manipulative in other ways, no one can convince me that he's a good guy.

You guys are seriously feeling bad for the sunbae? me personally, i don't fw him. Dude is gay and tried to kiss a straight guy out of nowhere —creeping the guy out. He didn't stop at that and was uncomfortably persistent on chasing the uke—to the point of manipulation. He saw that Ik-su was puzzled and confused so he took that as a chance to bind him to a "casual relationship" with him. To put it simply, Ik-su was dumb and the sunbae took advantage of that. Even without Dohun's interference—this relationship wouldn't have lasted long because it was clear as day that Ik-su was not into him and this was all one-sided from sunbae's side.