I feel like all of this is her own fault why does she get a second chance? He gave her a couple of complements for her summoning (didn't pay attention to her body since he's gay) and she mistook it for love, in fact when does he ever tell her he loves her, unless that's all being glossed over and its written in a LN which I assume so since they get engaged. He asks her to do some outrageous things and she said yes because she was in love. He was definitely using her and taking all the credit but she was ok with that, even said so herself. She was ok with her terrible physical state and the fact that she was going to die for him. She knows he would still have to move on, being the next emperor, and eventually have another fiancee once she dies. I don't understand how she can be ok with all of that but then say she's dying in vain when he's with another lover. Nope, you served your purpose dedicated you life to him and made the duke look good, that's what you wanted to do and you did it. Anyways maybe this next life she'll have a brain.