The woman (in this Ask HN) did not do anything wrong. Firing her would not be appropriate.

> If two employes can't resolve their own issues without involving you then you don't need them.

No employee should be subject to harassment. And as a consequence of being harassed they should not be cast aside. Part of being a boss is dealing with these situations. Even if dealing with it means handing it off to a lawyer and HR to resolve for you because you don't have the time or expertise.

> If the innocent party was truly free of blame you can always hire them back.

I can't get my ex back. Firing someone burns bridges.