Maybe since she saw him suffer from guilt in previous life she do not want to see him do the same. Would you let someone ruin themselves just to let them feel a moment of releave and after that ethernal guilt? I hope it gets resolved similarly as in the Survive as the heros wife. Also the aristocrats "only" spread false infos about her and accused her accordingly to them. I do not think it was mentioned any clearer than that, so I do not know why the emperor was unable to uncover the truth. It was his mothers choice to kill herself and his sister. It was cruel for them to die, and I still cant seem to understand why did she take her daughter with her to commit suicide. But its the plot so I will just accept it that way. Also I think Lise's father was also killed by Linden, so she forgave him even that, not just him killing her. (=・ω・=) but these are just my toughts and not like they are absolute or anything.
i think elise is crossing a certain line that she can never fully understand here. i don't agree with her opinion and i certainly don't think she can fully sympathize with him. yes she was executed by linden in the past, but i guess she did had it coming with that kind of attitude and personality, but to have your family killed by a relative on purpose is just too much. but i guess i would want to keep his sanity intact if keeping him from killing another person, but who's to say whether its effective or not anyway