Pennsylvania is an at will state in which you can be terminated for a good reason, bad reason, or no reason at all. You cannot be terminated in violation of "Public Policy" which our courts interpret to mean statutes enacted by the U.S. Congress or the Pennsylvania Legislature. When you are terminated because of your "protected classification" (i.e. age, sex, race, national origin, disability, and in some localities gender affinity) it's called "employment discrimination," not wrongful discharge.
There is no cause of action for discrimination where an employer treats one employee differently than another based upon a consentual relationship.
To put it another way, whether you were the source of the comment, or merely repeated it, being terminated for doing so is not unlawful. It may not be fair or reasonable, but it's not unlawful.