Responses
Well, if you see the flashbacks, seem like they both didn't want their parents to know. The ex didn't even want to hold hands in the public. He didn't DARE to ask the uke to do it, why does the uke announce it to his parents? Remember the uke wanted to hide his current relationship as well. It just happens that they got found out. Morever, his current bf is very daring, that's why he changed. The ex doesn't have the right to ask the uke to commit to their relationship, if he couldn't do it himself ╮( ̄▽ ̄)╭

I actually don't dislike the ex. Like he shouldn't have cheated, but if u think about it from the ex's point of view, the boyfriend that he's been dating for years hides their relationship from his family and everybody else. They've been dating for years, and MC couldn't commit by even letting his family know. That's got to hurt. Follow that up with MC telling him to go on blind dates. I'd be hurt too if the guy I've been dating for years tell me to go on blind dates with other people.
MC's a different dude now, but he wouldn't be this way if he didn't realized how his cowardly ways affected his first relationship. It's like those relationships where the couples date for years without marriage and then they break up cuz one of them wants to get marry. Next thing you know, the one who didn't want to get marry gets marry with the next girl. The first girl who wanted to get married gets left in the dust with hurt, bitterness, and time wasted on an fake, uncommitted person.