If this were someone else, Karkat, she would feel no guilt about digging in the knife and twisting it, telling him sometimes nothing can be helped. You will never be able to save everyone. The unkind truths of a time traveler; some things can never be changed and never prevented. Aradia is used to casualties, and some of them have been close friends, romantic partners former and present. There's no point in blaming yourself for something that can never not happen, has to happen.

"I know you don't," she tells him quietly, because whatever this is it's not about her trying to teach him a lesson or guide his actions. And even if it were, she wouldn't do it the way she's done for others. "Tell me what happened?"