@Decoy I agree. Although Marie can make them docile with her promises of love, it's still a shaky and temporary solution. Now dealing with the issue of their psychotic behavior by tackling the root cause would help reduce the risk of them turning on the princess. However I still believe it wouldn't work because Marie has somewhat attempted this strategy already. When she had to find the reasons why those women wanted her dead, she ended up finding that it's because of psychological unbalance. Emile was fed up with being ignored, Yuuki couldn't stand being seen as the perfect prince when she was compared to Marie, Cirsia is a manipulative sadistic brat, Lafine has serious mother issues etc. I concede that Marie exploited more their mental issue than she tried to fix them but I don't think she has the vision to consider this kind of solution, at least so far