That makes so much sense! Though I still don't fully understand the whole 'sacrifice' plot point Why is the MC marrying Shu and being sacrificed good for the saintess and the kingdom/temple in general?
its probably just a prophecy, like the prophecy probably want FL to marry someone who could protect her, I'm not sure why FL and the saint is connected but, in the later flashbacks when FL died, saint's power disappeared thus could not protect herself and died as well
I'm not sure if its vice versa like if the saint die does she die too? but the latest chapters are telling us otherwise
That's a good theory though. Thank you for sharing Can't wait for the next chapters!
She is probably growing weaker because the saintness used her powers to revive someone which is a taboo and MC being her "sacrifice" or whatever they called it, she is suffering the consequences as well