I think she believe that her sister can use her power only through love which would explain her decision then but i don't really know XD
As per the precious Story, Diana is the who has power to cure blake, so Ancia assumes that only she can cure blake even now.
whole story is lot more twisted. U need to wait for future Update .
But Diana didn't fall in love with him in the original story (￣∇￣") I think, because she ended up with Richard, the 1st ML in the OG story
Yea, hence why I said, why can't she ask her to use her powers to cure him in the future? ┗( T﹏T )┛
Since Ancia didn't die, she is only one who can cure Blake now, but she doesn't know she has that power with her and she believes Diana is the one who has that power to cure blake.
don't worry later Ancia will get to know about it
Do you how long "later" will take? ╥﹏╥
Do you know**
I can't guess how many episodes it many take.
But soon Blake health will deteriorate, so to save him ancia will do research, and she will find out all truth about the curse
That means that soon she can cure him right? Σ(っ°Д °;)っ
She will cure him and disappear, actually she was forced to disappear.
NOOOOO!! It looks like we're not even in the first quarter of the story （/TДT)/
There is still lot of twist and turns, just wait and enjoy!
If she believes he got cured by "falling in love with Diana" then why don't she think that he can get cured by falling in love with her? Since the cure is "love", otherwise if she believes her sister's powers was the cure then why don't she just ask her for her help? #－.－)