that's how it happened with noble families. if your crime was bad enough the entire family was punished as an example. it was some crazy shit but it is true to history.
These authors have bo idea how trauma works that's why characters behave this way. While I do love Elise and many characters in this, I can't help but notice just like you pointed out how unrealistic that part is. She was shown having nightmares maybe once. Then, all of a sudden, she became totally okay with going to bed with the guy who made her head fly in her past life. Even if she was the villainess of all villainesses (not true at all) and even if her death was justified, it doesn't mean that her trauma is going to disappear. Every time she sees him she should remember what happened. That's how brains work. I wish the author had just made her lose her life in an accident after being divorced or something in her past life....at least that way, the death does happen but isn't directly linked to the emperor (crown prince at the time)
I just don't understand how fl is ok being with someone who literally executed her and her entire family, I mean even if fl is the most Evil in her 1st life like won't she get nightmare if we think about it and he also killed her family, if she loved her family a lot then how she is fine with being in love with a murderer(from her perspective and also it was unclear why her entire family were executed in first place like she was evil not her family and even if they supported her they were just taking her side as a family they deserved punishment not death sentence) if someone you dearly loved was killed by your partner(even if it's their mistake) you just can't forgive the partner especially if it's your family who were always there for her(fl) till her last breath. Its just shows fl's priority whenever I read this story it always comes to my mind everytime.