-Iwaizumi feels like the second male lead in your story as he watches someone else fall for you instead. Which was his best friend, Oikawa. It hurt seeing all of it. He's the first one to fall for you yet he ignores it in all these years knowing that he should keep his feelings hidden. You three grew up together and he doesn't want to destroy what the three of you have created for the last years. So, he did what he does best. Lie and hide his feelings to you.