Ya pretty sure it was his punishment for messing with the timelines. The web novel explains it rly well but it’s been ages since I read it and obvs don’t want to give you any spoilers
Spoilerrrrr
.
.
.
.
.
.
.
.
1st timeline we have sweet Sa-Young and strong Eui-jae, Sa-young dies first and Eui-jae turns back time with himself as an anchor.
2nd timeline Eui-jae is sick and weak because he's anchoring, Sa-young develops an insane overprotectiveness and a shitty personality, because he's just so worried about Eui-jae. But Eui-jae still goes on and dies first. Sa-young turns back time and becomes an anchor but bc he's not as strong as Eui-jae, he stays wandering the ruined world forever.
3rd timeline West Sea rift appears which is I think the first of ruined worlds (bc Sa-young is in the second) seeking out Eui-jae who opposed it.
Right now Ga-young was sucked into 2nd world.
In the second timeline, Eui-Jae turned back time after Sayoung's death, is that what caused Eui-Jae in the thirth timeline to be stuck in the West Sea rift for 8 years? O.O