it's been obvious that Nanjo is already in love with Mok-yeon. I knew that before, but today I binged the whole series and I'm very convinced he is.
To my understanding, in chapter 28 when he asked Mok-yeon if he's really kept his end of the deal and not slept with Sunhwa, that was him checking if Mok-yeon has been loyal.
It's also clear in the kiss scene in chapter 29 after he confessed he's been avoiding sex with Sunhwa because Mok-yeon leaves bruises on his skin when they have sex.
But even before that, Nanjo has been indulging Mok-yeon in several chapters. and his reactions too. in the chapters where Mok-yeon visits him at home, he let's him drag him along on a "date" then tells him how he "likes" sleeping with him and also, how his hand reacted when Sunhwa told him that Mok-yeon doesn't eat seafood, because he remembered Mok-yeon making it for him. The ultimate scene of his indulgence is in ep 30 when he literally choked Sunhwa, choosing his moment with Mok-yeon.
Nanjo isn't dumb. I'm pretty sure he knew Mok-yeon had feelings for him. He probably doubts him because of Mok-yeon's past behavior but he's fully aware of it, same way he also likes Mok-yeon.
I hope they don't start making out and clear everything out first! I want both of em to fall for eachother sincerely not like tht physical contact shi again .