it doesn’t have a novel, and taejun already knew that geonwu had feelings for him. maybe you could say it was more like a presumption? but he believed that geonwu had feelings, but he thought no one could stay completely unaffected by seeing someone their like constantly changing partner (it was like he wanted to test geonwu’s feeling by having sm fwb) you can read ch21 again

Soooooo I am a really impatient person. Does this have a novel?
Also funny enough I can't really hate the ml. I guess I've read too many toxic stuff that even though I don't hate ml doesn't mean I approve of how he was. We as reader's are privy to the God view. As far as ml knows, mc is just a friend he can actually trust. He didn't know mc was in live with him.