Perhaps the reason that Lady Melissa acted that way was because of the fact that she had anger issues- though she was able to control them quite well, at least for most of the time.
Or maybe it was the fact that she was bottling up all her feelings, tossing them to the side as if they were unimportant- well they were unimportant, at least Lady Melissa considered them to be unimportant.
Or maybe it was a mix of both of the two reasons above, after all, having anger issues and bottling up all her feelings? It was a disaster that was just practically waiting to happen, and when it did happen.
Oh boy did things get wild, Lady Melissa could be screaming- while breaking down, after all, everyone would always feel better after breaking down and screaming their lungs out (i can guarantee you that this method works from my first-hand experience with it).