I gotta say the writing in this game really picks up after a while. I found myself mostly speedreading through the first Cecille training cycle, but beginning with Sera, things improve a lot. I think that if you strip away the fantastical background and hardcore BDSM/cucking themes, this game is great at capturing the spirit of the sort of pillowtalk conversations people at the early stages of a relationship have, especially the "forbidden" ones (cheating, taboo breaking, etc). Same goes for the way the characters are drawn in the afterglow scenes, they're spot on.
The wider narrative themes, of the need to choose between love and duty, of a struggle against having to live a life that somebody else already planned for you, of a pointless, violent conflict forced upon people by god-like beings, all of those are done very well too. It all reminds me of the game Demons Roots a bit, in that regard.