Saying "hello" to each other after Yule left the hospital doesn't mean they started dating again...
Actually they ended up together. Kyungsoo said that he will not be happy for the rest of his life because he will have to deal with yule for the rest of his life
No, I personally didn't take it that way. He will have to deal with Yule for the rest of his life because he will be forever trapped in the past, which is understandable taking into avcoint all the shit he went through. So, he will have to deal with Yule forever on emotional level, not because they're dating or something.
That was my interpretation too. If he did end up with Yule, there wouldn't be a "what if" scenario with Yule. Him saying hi to Yule was just acknowledging that Yule decided to continue following/being in his life even after he had decided to end things with Yule.
It was more at self-acknowledgement. Kyungsoo voiced that because both Yule and him hurt a good person (Dong-Hyuk) and if they continue to cross paths or be involved with each other, they will be unhappy together for the rest of their lives. Similar to "misery loves company."
But we still don't know whether the next chapter will be "what it" scenario with yule. Next chapter might be a side story or extra of yule and kyungsoo.
The final chapter has already been published, and yes it concerns a "what if" with Yule. We have been discussing it in the comments if you just scroll back. Personally, I thought it was the most likely scenario out of the three, even if ideally we all would prefer if Kyung-soo ended up with neither of them.
Why is Yule next? I thought they already ended up together?