No one in this story is perfect, which is what makes the story feel so realistic. Junyoung is resistant to being with Sihoon at first, but he can't help falling in love. Sometimes, we do get swept away by our emotions. However, that doesn't mean we allow our emotions to control us forever and we could still choose to do what we believe is right. Yet, doing the right thing doesn't always guarantee your happiness... Junyoung had a tough situation on his hands.
A bit of a spoiler, but Sihoon did push Junyoung away for a bit... Sihoon did cause some confusion with Junyoung. Junyoung feared that Sihoon would grow tired of him, which is why the youngster didn't confront Sihoon and never asked Sihoon to be in an exclusive relationship. Junyoung was just afraid and didn't have previous experience to rely on.
If any of us were in Junyoung's position, it's not easy to say what we would do. Junyoung is sincere and looks adorable, which we could see how Sihoon fell for him.
SPOILER: Junyoung did intend to have sex with Hyuk but it didn't happen. Junyoung even pushed Hyuk away and said he wasn't ready. Junyoung just couldn't forget Sihoon, just like how Sihoon couldn't forget Junyoung.
As much as Junyoung misunderstood, Sihoon also never talked about his family life to illustrate it clearer that he's not married... Junyoung and Sihoon don't know a lot about each other's background to be honest. They still have a lot more to learn about each other.
Throughout the entire story, we could see Sihoon and Junyoung fall in love with each other. They fall in love with the way the other person treats them and the way they look at each other... They're both very genuine.