Honestly, I don't mind her being civilized with someone who killed her before because she was in the wrong but falling in love with him is cringe. This is an issue I have with a lot of stories. You can never forget being stabbed and killed by someone.
I ship the couple from Doctor Elise but she suffered from nightmares for the longest time and eventually, the webtoon brushed over it but that'll never end. That is just human nature.
I wish these stories didn't involve the killing part. If he banished her or something I might not complain but remembering how you took your last breath in agony because of someone, even if they're not in the wrong, is shitty when you're just acting lovey-dovey with them nafterwards.