Feels to me like he decided that perhaps being an idol wasn't for him.
When you do image translation, there's a line which was translated to: "Carrying the expectations of the fans and the agency led to my mental and physical health being damaged, to the extent that I was in a hurry to return to my activities, but my heart didn't follow".
if you look at posts he liked on Twitter after he went on hiatus, and before announcing his departure, you actually get the same sense.
He did write that he will continue supporting NIK from behind the scenes.
I think he mostly wanted to return to focus more on his dance expertise - the things he did before NIK and G-EGG.
The irony, by the way, is that initially he wasn't supposed to be in G-EGG as a trainee. Originally he was contacted due to his dance expertise, and he was asked to be amongst the staff, or amongst those scouting possible trainees with exceptional dancing skills... from what I remember from G-Egg, He was the one who asked to be given an opportunity to debut and be part of the contestants and not part of the staff.
He was among my favorites too.
