Did you see where I said an employer can fire you for any reason EXCEPT one prohibited by law?
It's when an employer fires you for a legally prohibited reason, that a wrongful term comes into play.
If the employer fires you because of your race, religion, national origin, gender, disability, pregnancy, or because you are over 40, that's a prohibited reason; you could file a wrongful termination suit.
If you were fired because you applied for or used a benefit or right that is protected by law, such as FMLA, workers comp, joining a union, reporting unsafe activity to OSHA or illegal activity to the appropriate outside agency, etc., that's a prohibited reason and you could file a wrongful term suit.
But if you are fired because your boss is a Yankees fan and you cheer for the Red Sox, that's NOT a prohibited reason and you could NOT sue for wrongful termination. If your boss fires you because you had a banana on your desk (yes, that's an honest to goodness, bona fide question I once answered) that's NOT a prohibited reason and you can't file a wrongful term suit.
And if your boss fires you and you can't figure out what the reason is, UNLESS you can make a good enough case for one of the reasons above that are prohibited, you STILL can't file a wrongful term suit. (Well, you can, but you won't win.)