I think most of what you do on your own time - within the law - should be off limits as grounds for termination. Especially if "what you do" means you GET MARRIED. Seriously, most of corporate America is married, in a relationship, divorced, dating, or otherwise...but it is not part of your employment terms.
Unless you are Scott Janke, the Fort Meyers Beach city manager recently fired for getting married. To a porn star, but got married nonetheless.
That's just crazy. HE didn't do anything wrong except (hopefully) find happiness and fulfillment in his personal life, yet was fired for it because of who his wife is. Ugh. Crap like this drives me crazy.