If I remember this right... then,
The MC was uncomfortable with Hyun-Do probably because of his emotions randomly appearing like that. And The MC got angry at him because of what he said, I don't really remember what it was but it was something that the MC was mad enough that caused them to fight
Because in pass life, his friend try to be close with MC.. but MC feel pressure since his friend is more famous than him.. He feel like his friend is mocking him but the truth is his friend really genuinely wanna try to get along.. Its just a misunderstanding
Plus they fight because the MC shout angrily at his friend and said like 'you can do it all because you get everything in life unlike me who has nothing' but the MC dont know that his friends also struggle in his life.. So they fight and MC avoid him at all cost
Mc's friend is so manly, even as a young boy. His friend seem so nice, why did they have falling out in his previous life again?