Ooooook!

Yes. The butler, in self-preservation betrayed their family. If i'm not wrong, for her family to be targeted so much, it must've been a civil war.

Her father seems hold a high position in the military.They are a Ducal Family, what's more due her mother as a business savant, they are very wealthy. They must have a large influence in court (and might have even possess the power to move the army)

So to the opposing faction, taking their house down is a must. First, take down tue Duke during the expedition (?), then assassinate the heirs to end line. A spy is necessary= Butler, it's a good position for you.

The friend's brother, trying to find clues on why the brothers died, was also killed from meddling into deep waters, so he may have been silenced.

Due to the family demise, her mother got sick and was not able to work. Their house fell into ruin. With no one to back them up, naturally they would leave her alone, as a trophy for the successful demise to regard or maybe they spared her, only to suffer more. Since realistically speaking in her situation, a fallen noble in poverty, her end will not be good. The only reason she stayed alive for so long is due to that loyal knight.

As for the silver haired boy, he's the ML as for who he is, the only possible answer based on the premise that my theory is right, he can only be the prince. Either, he's the crown prince who died (killed) too early that caused such mutiny in succession to the throne, or he's one of the rebel prince, that who won the throne in the end.

Anyway, some people spoiled that he'll appear by 50+ chapters. Hehe. So, hang on. (⌒▽⌒)

50 chapters (⊙…⊙ )

Omg thank you (╥╯﹏╰╥)ง , i finally get the gist of this thanks to your explaination.
It's deeper and more complicated than i thought, but if the butler is the spy... Then , who is that curly purple haired guy in the raw? Our mc looks like she hates him alot, more than the butler (i think)

i only need one thing clear up. who did she supposedly killed in the prologue? her father?