From reading the translated novel, ML basically just says he likes MC as a person and would want to be friends with him for a long time. They both agree, let’s stay friends! But slowly, really sweet moments (moral support, even playing with each other’s hair to pick out gray strands, hanging out, running into each in public) happen between the two with no romantic or desperate intention from MC, which slowly draw in ML until he basically realizes he’s down bad.

So what's the end of that convo?
they're staying friends?
make him pay for what he did