Kyungsoo made the right decision. If I was dating someone and found out that they had purposely hurt other people, I'd find that a huge red flag. If I confronted them with it and they wouldn't show the slightest hit of remorse or even admit that they had done anything bad, I couldn't remain in that relationship. No one is obligated to stay in any relationship. Also Chowon needed to take those steps back to reflect and atone, or he wouldn't have been able to be in a healthy relationship with Kyungsoo.
He would actually told him thay he wants Chowon to change on the 1st place and not simply leaving him behind and only waiting for him to change instead.. some people like Chowon might interpret it wrong way on the 1st impression when he ignore chowon instead of saying he wants chowon to change.. the only wrong step of Kyungsoo is he doesn't tell chowon to change but jusy simply leave chowon behind with all his anxiety
I know exactly what's it feels like cause I've been how Chowon feels.. the reason he overdosed himself was what I did before too..
Look at how happy Chowon is when Hyesung accept his apologise I'm so happy for him.. doe tbh.. I'm still angry towards Kyungsoo.. but Chowon! Your step is beyond excellent.. Apologize is 1st step of all mistakes you ever made.. also! Kyungsoo you better not to leave Chowon again (︶︿︶)＝凸 or I would rather have Chowon with someone else