Raffine's Plan: Save My Favorite Character

I'll marry the male lead myself! Raffine is in a predicament, and there are three reasons why. One, she's been reincarnated into a super angsty, highly depressing novel. Two, her older brother is destined for death in said novel. And three, the only way to save him is by marrying the male lead. What the hell is going on?! (Source: Manta)