I dunno, considering that Maria is supposed to be a ex-SHIELD agent (who, whatever her qualifications as the Director, was supposedly excellent in the field), she's coming off as so scrambled and out of it here that I wouldn't blame Natasha for writing this off as a nervous breakdown. And even if it is genuine, she still has to figure whether it's worth getting dragged into the large cloud of trouble that is very definetly following Maria.