Tales of Vesperia rant
I'm sure that this has been ranted about before, but it's worth repeating. Naiveté is not synonymous with stupidity. There are things that even people without who've led sheltered lives can be expected to understand.
I'm pretty sure nobody needs to explain to Estelle what a "kiss" is. I mean, seriously. She's locked up in a castle her whole life, but she's also been reading her whole life. It's safe to assume that she's read a romantic book at some point. And even if she stuck strictly to history books, which is doubtful, than a huge part of history for nobles was who marries who.
Even if she never ever read about romantic or sexual relationships, then she must have at some point notice a romance among the servants and knights in the castle.
And this is mostly subjective reading, but I get the feeling that she had a a crush on Flynn at the beginning of the game anyway. Somebody should write that fic. I really don't think she was that completely oblivious.
TL;DR, it makes no sense that Yuri would have to explain to her what a kiss is.
Also, Judith is not a whore and you suck for calling her a whore.