This has got to be one of the best endings for this type of series no "Ah theres actually a way to solve the most important problem that invalidates everything the characters went through" Choices were made and consequences will be met no perfect solution and there is a certain romance to that type of story.
This just reminds me that one day I want to make a "manga/manhua/manhwa ending" tier list. Not necessarily ranking the actual ending itself so much as how it was handled, if that makes sense? F tier is "to be continued" and getting your hopes up but then not getting renewed (example: "To Another World On My Own"). Another F tier is overstaying its welcome and not ending when it needs to (example: "Earthchild" had a fantastic premise and beautiful chapter 1, then got on a steep downhill slope and snowballed). Getting axed and "the adventure continues in the wn" is probably D tier (example: too many to name, tbh. Pick your favorite). S tier would be something like "Her Majesty's Swarm" which got axed and dealt with it by
having the manga have a completely different ending than the wn to compensate. The wn continued, but since the manga couldn't keep going it got it's own unique "bad end" that was actually pretty satisfying. Or rather, it was very much unsatisfying but in the exact perfect way. The kind of ending you absolutely hate in the moment while reading it but come to appreciate later.
Something like this would maybe be B+ tier? Doesn't overstay its welcome, but ends maybe a bit prematurely and didn't see the full potential of the manga, but at least didn't have a cheap or cop-out ending. Fairly happy ending, maybe a tad bittersweet, but was handled fairly well for the most part. Again, I still feel like it could have continued a bit more past this part to tie up some loose ends with the other succubi, but all in all handled alright. Not the most satisfying ending, but I've definitely seen far, FAR worse.