Despite her flawed argument delulu-sensei closes with a strong point. Of course someone's going to have some anxiety when their partner goes through such a drastic change in such a short time. Change is scary by default, even if it leads to something better.
One one hand, Momoko is displaying the
tendency for women to behave emotionally and to believe the worst. On the other hand, when someone starts changing behavior and appearance without warning or explanation it is
one of the red flags that scrutiny may be required. Example: Your wife suddenly loses weight and spends more time putting on makeup before work or meetings.