Here is the libertarian position on all this gay marriage, homosexual military, homosexual immigration, adoption, polygamy stuff.
It is why you are hearing more and more GOP rinos going libertarian.
1.3 Personal Relationships (libertarian)
Sexual orientation, preference, gender, or gender identity should have no impact on the governments treatment of individuals, such as in current marriage, child custody, adoption, immigration or military service laws. Government does not have the authority to define, license or restrict personal relationships. Consenting adults should be free to choose their own sexual practices and personal relationships.
This is true and correct and the way it should be ... but you have to add to it first.
Society is entitled to it's own agenda. Government has no business enforcing tolerances for the intolerable or vice-versa.