I try to explain that what she means to say is that she is disappointed that she can not have what she wants. I also try to explain that she might nuance her request a little bit, perhaps by substituting "Mommy, would you please" in for "You have to . . .". Sometimes, she changes it up with, "You weewy weewy [really really] have to . . .". Nope. I don't.
In addition to announcing that her feelings are hurt, Fiona often declares that we are not best friends. Then she might storm upstairs and slam her door. I don't mind this so much. She calms down in her room while I savor the silence downstairs. Alternately, there is screaming and crying and snot through which I do my best to sit quietly. Other times, there's just a bit of pouting and then she's over it. You never know what you're gonna get.