In chapter 2, the more evidence he found, the more depressed he become. He want to leave at that time, but his girlfriend beg him to stay which soften his heart and he decide to stay.
In chapter 3, he find more evidence that point out his girlfriend cheating and the possibilities she has kid already. He literally broke when he saw the baby that look like the man cheat with his girlfriend.
In the ending, he tried to relieve his stress with basketball. Failure to make the ball enter make him feel he's worthless as a man but Succeed in doing it make a girl who watch him adore him and they start relationship.
It's a good story of a man who tried to love his girlfriend who didn't love him back and decide to break the ties. At the very least I want to see the scene of him confronting his girlfriend or bit of story at all which didn't really happen.
He's spineless coward, but he got determination to find the hurtful truth and not averting his eyes from it. He is at fault because imo it's partly your fault that our partner cheat on you. Still, he try to fix their relationship on many occassion which turn into failure. At the very least, he make effort for it.
But, I like how he can still look up even after what he has gone through.
Too bad for the ending though, and here I thougth he will try to win his girlfriend till the end xD. Sometimes, giving up is the right choice, and he has indeed done the right thing.