beta
i think that a young past!yeon was the one who linked past!yeon amd past!kihoon and since their red string was forced/not real, it lead to a bad ending. the red string that connects current!yeon to the current!kihoon is probably just the false/forced red string from their past life that got reactivated when current!yeon prayed to the stone (not knowing he had a previous 'deal' with the stone in his past life) and the red string connecting current!yeon to that cutie with short hair is his current life's real red string partner.
the misfortune that current!kihoon experienced throughout his whole life was probably reparations for how past!yeon made a false red string connecting him to past!kihoon which might also be the reason why past!yeon died(got killed?) which left past!kihoon the sole bearer of two people's misfortune which carried onto his next life.
if current!kihoon didnt go to the stone with current!yeon, their red string wouldnt get reactivated and i fully believe that they would've gotten together without it.