I don’t think you need a fixed reason besides wanting to be with the other person. Enjoying their company and falling for small quirks. There is time to discover and create similarities and stuff like that. Nothing huge and no wow moment. For a story it’s a bit underwhelming, but mr. Kwon didn’t seem to be too familiar with falling in love. I wish the author would’ve given him a proper backstory for us to understand his position on dating properly… but like others said, because of the state of the author, the ending got rushed QuQ

what gets me about this is that mr. kwon didnt really have a reason to start liking danwoo, after all that "i dont date" talk there was no lightbulb moment so why did it change for mc? we will never know i guess it was just for the sake of the plot
also it makes no sense why dawoo likes him cus he treated him like SHITTTTT, bro really fell in love after having sex