I read a spoiler here some time ago that kind of excuses his behaviour.
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Apparently he was drugged through a longer period, making him paranoid and violent, which is why he was so shortsighted and aggressive when it came to Tia...
U are correct
Yeah I know but Isn't it strange 'WHEN IT CAME TIA' he behave like a total DICKHEAD? That only means Ruve hatred toward Tia already deep rooted and the drugs only enhance the effect. What I'm saying is Drugs or Alcohol can make people become violent, killing or raping people in the worst way but they don't discriminate, or are you saying 'HATE POISON' that make someone hate and abused a certain person exist? Or are you gonna say that Ruve hatred toward Tia are justified because his father treat her kindly but cold toward him, or because everyone keep comparing him to Tia, or because his father figure 'Duke Zena' always badmouthing her every now and then, or just because she doesn't smile much or because of a word she said about her mother that she doesn't even remember or even rumors from the palace maid? Ruve are so sweet toward Jie Eun whom he just met, just because she spoke a sweet nothing words to him, on the other hand he know Tia since she was a baby, if you see his flashback, Ruve said so himself, Tia and Her Mother were the only one who treat him with kindness and that was before Tia return back to the past, since she reincarnated at the age where she already lose her mother and have no memories of her childhood, So Ruve know the child Tia who is so pure and soft hearted and the shock of losing her mother at such a young age make Tia lost her memory. And Ruve also close to Tia Mother, and he witnessed Tia Mother dying protecting her precious daughter and in her final moment she ask him to take good care of Tia. So yeah, there is no excuse there.
TLDR
Listen, I just mentioned the spoiler. And I said it "kind of" excused it - not entirely.
But yeah, he didn't like Tia very much bc of various misunderstandings, is what I gathered from the spoilers.
But we'll have to wait and see to know whether the explanation holds, or if it's a bunch of bs that we should rage about... ┑(￣Д ￣)┍
If The Prince was the one getting reincarnated and having memories of his past life, and in his second life he decided to change himself for the better then I believe he deserve a second chance. But NO, Tia wasn't even an evil bitch in her past life, she just the quite type, yeah I get it people always misunderstood and think the quite one aren't nice person, cold blooded blah blah since that's what people always said about me but getting abused because of prejudice are entirely different thing.