To everyone’s who like 'Kris should have left before the comeback if he already made up his mind then / he shouldn't have given fans false hopes about the concert when he knew he wasn't going to be there' etc, I have one thing to say. When your heart tells you to do something, it is never easy to put it into actions. Kris was unhappy in SM, but he has also gone through fierce competition/long years of hard training to obtain his position in Exo.
Think about it, you might hate college, your job etc but can you quit now? You have to plan your departure and wait for the right time. Rather than thinking he shouldn’t have participated in Overdose, we should be thankful that he stayed to not disappoint the fans with an incomplete comeback. Fans wanted a tour concert, but do you think SM/the members would have agreed to it if they knew Kris was going to be absent? Even though he was unhappy, he did Exo a favour by supporting them and pushing them to the highest level of fame before leaving.
He left smiling with the members rather than telling them how he felt mistreated and leaving with both sides in disappointment. He left politely without shaking the foundations of the group. He created only happy memories for all of us with OT12, and we should be grateful for that.