He's not denying it. He was upset that mc is sticking to the line that he himself has drawn while he has been crossing the lines for quite sometimes now. He in fact knew very well that he has a soft spot for MC.
Mc isn't sticking to the line well though, mc did that early meet up. It could also be that ml realized mc is starting to see him in a different,comforting way so he's trying to break that off
No, he doesn't know. A lot of their miscommunication happened because they misinterpreted things. You have to remember this story was being told from mc pov. Of course we're able to tell he cross the line. But ml doesn't know anything until mc starts talking about it. He's acting like this because he's upset that things doesn't go the way that he intends it to be - in which taking care of him in whatever ways he could. This is the line that he's crossing. He literally said this before mc cuts him off. Now mc has reminded him clearly about the nature of their relationship, he was trying to keep himself in check.
You will learn in later chapters that in fact, he will not be able to do so.
Exactly. At the last scene of chapter 31, Han prb sulks that Seo Dan doesn't want to talk abt his problems to him
So basically my guess is the seme realized he's developing feelings that's why he's trying to asshole his way into denial