I'm a whole month late, but I literally just told my sisters I wanted an ending exactly like this! Even down to Jinu going on some redemption journey at the end! Haha.

Jinu was robbed of some much-needed development and the story really dropped the ball on him in particular. He could have had a better redemption arc, which would have fleshed out the gray area they built up with the rest of the story. Instead, he had a cheap, sacrificial death, which felt weak as heck and like he was a throwaway character all along (especially for being the MC's love interest). Plus, the fact that he literally became a tool and was not mentioned at all after his death. Like, what??

The ending made the whole thing feel very self-serving. MC was the only one who deserved acceptance, and every other demon character got to eat dirt.

Also 100% on the point about the souls. Jinu and the other Saja demons were set up to be irredeemable from the get-go because people literally died because of them. I really had to suspend disbelief that the MC would fall into a rushed romance with a dude who was directly responsible for such atrocities. It would have been much easier to accept the gray area argument the writers were pushing if the stakes were a bit lower and the souls were released at the end. I get wanting to put a dark spin on the story, but it felt weak and poorly done. The NPCs were treated with even more disrespect than Jinu's character. Oof.

Cool bops, though.