People would think its copying Frieren
Well, in a way, it might be (since this series was written after Frieren).
But both the story diverges a lot and explore aspects which Frieren didn't cover (atleast yet).
I mean, while it's not mentioned in Frieren, but this series does give an outlook on why Frieren never considered accepting Himmel, and how the Curse of Love is like, which Himmel suffered but we never got clarification, which this Series gives with how lives of short life-span race is messed-up when they fall in love with someone from a race with long life-span.
Also, Frieren is a story which covers a small aspect of Frieren's long life.
While this series is based on the PoV of a long lived Elf, aka., how the world of short life-span develops and ends, leaving behind only memories and sadness, and how those who are alive have to live on even if they end up alone for the rest of their life.