
THAT FAMILY IS FULL OF SHIT!!!!
The parents are ABSOLUTE MTHR FUGGERS!!!!
They adopted the MC because they couldn't produce a child and when they finally DID they FUGG UP!
They neglect the adopted child, leave him up to his studies and when their own child(ML) points to the adopted child(MC) for getting hurt they THEY FUUGGING BLAME THE ADOPTED CHILD!!!!!
FUGG YOU BROOO!!!

I think ML is either an over thinker or a person that jumps to conclusions. And I get that FL is an introvert and one of the hardest things to do is communicate.
but lets face it, their both introverts, that's why they only say few lines and go their own separate ways after some tea and eatery later. That IS before FL shows that wasn't all that she was, and expressed herself more
In conclusion... They were both at fault... (。-_-。)
Its great that she took advice and studied the book tho, it's one of the things I like about her as an FL. DOESN'T EXCUSE HER OF LEAVING KIDS ALONE ON A BUSY STREET THO! just saying
And the ML, the boy needs to open his eyes and not just expect people to go with his wims, wait for him for YEARS then think it will all be alright without communication and reassurance, on the person he's suppose to MARRY, and that they'll still be in a happy ever after.

I think her mentor in her previous life already knew of her identity, after all he knew what knowledge to give, what essentials(?) to provide her with. And taking her in without batting an eye yet betraying her like it's common sense doesn't add up.
And I think (this might be a stretch but) what if the people visiting the duke's estate was actually her family, teaming up with the duke to find her.(there could have been traises of her somewhere)
The mentor didn't like the way she's constantly progressing, and knowing how (maybe) HE was actually the one that killed the children at the orphanage (this is just my theory) and idk maybe changed appearance to mimick the duke, to fuel Ria with anger to take revenge.
Since she is constantly improving and getting stronger she's become more and more dangerous for them, he decided to discard her and betrayed her like that, while also mocking her family (killing two birds with one stone) like a "if I can't have her, no one should" kind of thing
There are still more theories, but it still doesnt have enough light to see it clearly. That's all
Except for the violence at first(for me that is) it's ok (not ok in real life but in a fictional sense) it's kinky for hardcore S & M
And we must keep in mind we all have different taste some people actually likes it some doesn't