I think the bottom(can't remember the names) forced the red string in his past life and try to change fate, that's why all this misfortune happens to him in this life. There was a chapter mentioned that it's possible to forcibly apply a red string tho there are consequences to it. Maybe in this life the top's red string was suppose to be with that girl
But didn’t the black hair dude tie the string to him first? I had the same theory as you, but the bottom didn’t initiate it (from what we were shown at least).
I think the bottom(can't remember the names) forced the red string in his past life and try to change fate, that's why all this misfortune happens to him in this life. There was a chapter mentioned that it's possible to forcibly apply a red string tho there are consequences to it. Maybe in this life the top's red string was suppose to be with that girl