
What if Lee Yeon is originally destined with the short-haired girl (the one where he briefly saw the red strings on their hands) but because of what happened in the past, where he forcefully connect the red strings to Kihoon, that is why they are now connected by the red strings, and as a result of forcefully connecting the red strings, Kihoon's has numerous misfortunes.
Now I know why he and Dr. yang has clicked. Because his bestfriend and dr. Yang has similiarities.