Later, in INU, we see Yoongi lying alone in bed, and if you really look closely you can see that the shirt Jungkook was wearing in RUN before he died was hanging there.
Yoongi, unable to live without Jungkook (his reflection), decided to burn down the room while he was in it and died to join Jungkook.
In Euphoria, we can see that Yoonkook were finally able to see each other again and are sitting looking at the scenery together like during their childhood, a childhood they desperately want to return to but cannot.
To be continued.....