There is no law that directly prohibits a supervisor from dating another employee's spouse.during a divorce.
However, the supervisor's actions may be what is called an "intentional interference with contract," which means that the supervisor is attempting to get your fired for a wrongful purpose -- that is, to get you "out of the way," and create a financial hardship for you, so as to make it easier for the supervisor can date your wife.
This sort of lawsuit ordinarily would be very costly to pursue. But, if the supervisor is engaged in this conduct while acting within the scope of employment, then you may be able to sue the employer for the supervisor's actions.
Also, if you are a member of a minority class (race, color, nationality, religion, sex, age or disability), then you may be able to claim that the supervisor's actions are related to your minority status, than it is to a personal dislike of you.
In my view, your circumstance is sufficiently complicated that you will need an employment rights attorney to assist. For referral, see this link.
Hope this helps.
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