
What exactly does Cain want from Arthur??? Like I'm kinda confused does he know Arthur is associated with Silas or something????

I had a full helpful reply written out for you & it got deleted ≽^╥⩊╥^≼
Short answer: Cain is looking for Silas, has no idea where he is, & has no idea Arthur knows him. In the course of becoming aware of Arthur, Cain realized Arthur's real good at his job, so he's testing him. If Arthur's as capable as he seems, Cain plans to make him help him find Silas. Cain's true obsession is Silas, he has a mini fixation on Arthur as a useful (& attractive) tool that could help him get Silas back

I need someone to give me major spoilers from the novel how does she escape the royal family and end up with him

spoilers
she breaks off from the magic spell cast on her by cerdina since childhood. it feeds on her loyalty to the crown, which makes her nauseous and gives her frequent headaches. a kurkan magician helps reverse the curse slowly. it's a pretty painful process for her but the ML is very patient and doesn't force her treatment. they even get separated twice, one by kidnapping and the other by her choice, because she wants to know how and why she got that way.

It helps weaken the curses. One time doesn't break it. So that is why they have to do it multiple times
Plus, Cerdina didn't need to use very strong curses the first time but she soon realized that her control getting weaker, and uses much more stronger curses later on.
However, the hardest part of the curses is that it prays on Leah morals and the difficult part was figuring out which part is her thoughts or manipulation of the queen. So Leah feels attracted to Ishakan, but is resistant to it. It can be mix of her actual thoughts and the control of the queen. Considering that a political marriage with Ishakan is far better prospect than that trash of a fiancee.
He really said am I so hard to care for
While kicking his feet xD
Oh poor baby