I'm confused. Is the emperor supposed to be one corner of our love triangle? Cause if that's the case, I'm out. I can barely tolerate abandoned empress and that's because the ml is nearly a completely different character in the second life, but trying to get me to be OK with a psychopathic, murderer who's okay with a child bride and perfectly find with ending the lives of the hero of his empire is straight up horrible and STUPID! Like... first of why didn't the knight actually put up a fucking fight? Why just let herself be stabbed in the back? Why not run away? What value does marrying the child of a dead hero help? Did you want the fame and approval of the people through that? If so, then why kill the knight? Did you want her bloodline? Then why the fuck not wait?
There is no feasible way to justify this murder/kidnapping/forced-marriage, and if you're going to do that AND try to get me to like this asshole, you've got another thing coming.