So hear me out!
If be my favourite series universe allows multiverse.
I have a theory that, Everytime kawi moved the glass ball, he went back into the past and everytime he changed something in past, a new timeline would open where things would be different according to the "new past"

Which would mean,  currently active universes

1.  Original universe: there is the original universe where kawi is a subtitler, and pear and pisaeng are getting married. and pisaeng barely knows kawi
2. pisaeng kawi besties universe: where kawi is pisaeng best man
3. and of course the last universe where pisaeng was in love with kawi and ran away from the marriage.

and i think everytime kawi went back in time, there was a kawi of that universe that has to continue living the life he created. so there is still an original kawi who lives the life of being pear's friend. and then the one who is pisaeng's best man late to wedding and the last one where pisaeng kissed kawi. 

its just  an arbitrary soul of kawi that keeps on moving around until he gets the perfect universe for himself