Can someone explain to me what’s the symbolism behind the thread sewing his heart? It pa...

It just represents the wounds Heejae caused him. When the scar stitches up, Garam's heart feels full and he's feeling better from the hurt caused by Heejae but when the thread breaks it the wound widens, he's dwelling on it or feeling resentful, opening the hurt up again

everything the person says above and also the fact that garam's heart is always stitched up and never really actually healed is symbolistic of how their relationship is fragile and its easy to tear apart again with a few words or a few actions