EDIT: I mean in the game. Her sisters and even her mother say that she isn't particularly beautiful.
Cassia is just jealous, she does everything to steal MC from Valentina, you can call it sister's rivalry.
As for her mom (forgive me, I forgot that bitch's name
) and Aelinia - on my playthrough I think they are just being grumpy because I didn't pick them)))
So, while "ugly" Valentina and her not so very "bright" sister Cassia are having fun with MC, mommy and Aelinia can rant behind their backs all they want
P.S. Personally I think Valentina is very beautiful, but to each their own of course