Blame it on not having enough chapters, the pacing is just all over the place. The novel hasn’t ended yet, at the time this comment was written and when the manga ended, so it’s another reason why the end is so half-baked. It’s a shame though, if the mangaka had taken a different path from the original source, this could’ve been a much better harem manga (that’s why most spin-offs for this are actually better). For its kind, there are a lot worse, but this isn’t that good either.