Mistrust an unexpected change of front. So,

Does your erstwhile frowning lady smile? "cherchez l'homme", or la femme.
Since

To arouse jealousy in another feminine breast is sometimes the motive of
feminine complaisance. Indeed,

Few women can forgo an opportunity of arousing jealousy, whether in a
feminine or in a masculine breast.--Bethink thee of this little fact, O
man, when next thy lady comports herself thee wards ultra-graciously.

To see the girl of thy heart--even if so be she not thine, nor not
nearly thine--comport herself with another as she does with thee--ah!
that gives a twinge to the masculine heart. Nay, lesser things than this
will perturb this irascible organ: that the other should admire her
charms--that she should accept such admiration. . . .. yet what cares
she that these discomfort a man? For

A man's discomfiture is naught to a woman. In sooth,

Take a woman to task for her conduct, and with how soft an answer she
will turn away your wrath, how deftly make light of your rival's
advances!

* * *

Man, when he has won him a woman, is, in his great greed of possession,
infinitely chagrined that he was not master of her past as of her present
and future.--This goes by the name of "la jalousie retrospective".