????

I bet laura is a shitty isekai protag and did it herself the sugar salt thing

i think no? or maybe??? but I also think that Laura is a white lotus type of girl, can be seen as angelic but hides the venomous side (￣∇￣")

Either Laura did it or the other options are
A) the dukes son lied
B) the game has some plot force that enforced that incident so the story would go accordingly
C) the dukes son put the salt in there to frame the fl and break the engagement