On one hand. They never listened to her in the first place and just up and decided to marry her to not just some stranger but to the second prince who is in the middle of a succession feud. With her lack of social etiquette skills, that is a bomb waiting to happen. And based off of my first impression of him, he is either the super haughty type that thinks it's a given for things to go his way OR he is the sporty knight type that would heavily clash with her being an introverted intellectual.
Now she is in the wrong because A: As much as it pains me to admit, you cannot just read books your whole life. B: She never tried to engage with her siblings in conversation, with as many books as she has read I am shocked she didn't have something to add about fashion or romance. C: Taking advantage of your siblings' guilt is just wrong.