There are arguments that marriage should be open to consenting adults regardless of their sexual orientation or relational preferences. It’s like a matter of government not making it its business to regulate what’s going on in the bedroom between mutually consenting adults. With same-sex marriage having been legalized recently in some states, do you think it makes sense to legalize polygamy, too? There are people who are indeed happy in polygamous relationships and are highly functional in them. Should government discriminate against people who have such a preference?
http://www.nytimes.com/2011/07/21/opinion/21turley.html