She's trying her best to reverse the effects of the charm or to completely nullify it, because in the span of time that they've been together, she really fell in love with the duke. Even though, the duke didn't even love her, but due to the charm's effect. So her plan was to nullify the charm's effect on the duke first. before she'll leave everything behind, including her own feelings.
Besides the chapter that you've read isn't really the official one, it's a prank from the translator, Happy April Fools~, take care and have a good day.
^This and if she left the duke right away he would've been killed by the King for refusing to go for visits(disobeying orders) plus he was also starving himself so she would accept the marriage.
Wut why would he be killed by the king ? N i mean she knws tht his puppy dog love is just an illusion n not real love isnt she trying to cast another magic charm on him right nw or was tht like part of the april fools thing ?
WTH IS SHE DOING SHES GOING TO CAST ANOTHER CHARM ON HIM THT MAGIC IS WUT GOT HER INTO THIS BRILLIANT MESS IN THE FIRST PLACE SHE SHOULDVE RUN AWAY AFTER THT NIGHT besides I feel bad for the duke she should try to reverse the charm before leaving its nit fair in him either technically