most likely because the soul that was in camilla body was the wrong one, they explained in the beginning that being in the wrong body causes rejection and hatred even by family members
Wasn't Rivi is Camilla's older brother?
From spoiler in the earlier...
Their mother didn't leave Ravi's bio dad, but because Ravi's dad are dead already and for the Camilla's dad, when their mother have relationship with the dad, it's because the dad actually has lost memory at that time, and when the memory is back, he also lost his memories about them and then leaving Camilla's mom, Ravi and Camilla.
Ah, now that you mention it, did Camilla's mom mistreated her? I don't remember it that much at that point since she is a different soul, I'm expecting no one ever likes her when she's a kid.
If he was Camilla's biological father, why did he let Camilla's mother leave him with Camilla? Or was Camilla's mother not actually a noble or was she a servant?I'm confused, Camilla's mother even found another man then gave birth to Ravi and after that left Ravi's father. She's really had good fortune when it comes to men(￣∇￣")