I'm pretty sure that what I'm looking for is a really angsty arc in a BL QT story. So in the arc, the ML was reborn and the og!MC was apparently this scum in their first life (IIRC he broke their engagement or something? not 100% sure though). So the ML put this handcuff or bracelet on the MC that had this curse on it. The curse made it so that the MC would freeze to death or something if he is far away or unable to touch the ML for some period of time. The curse makes the MC weaker and will eventually kill him, so the ML eventually regrets it. He got the bracelet from a healer(?) and the healer told him that he had a key, so the ML (or his subordinate?) starts looking for the healer. BIG ANGSTY SPOILER ALERT: . . . the healer lied, there is no key nvm i found it