In regards to goverment involvement in marriage, marriage would not exist in its current form without government involvement, dating back thousands of years. The marriage contract itself is a contract, not between the individuals involved, but between the couple as a unit, and the government.
Marriage was created as a means for a breeding couple to force the government to recognize both their relationship, and the family unit (including any and all children) that relationship formed. All couples at the time that did not have this contract forcing recognition found their families split up, and their property sold off by the government, against their will, when one member of the original couple died. Engaging the contract forced the government to recognize not only the constancy of the family unit, but the inheritance that unit provided to future generations.
As such, there is no marriage without direct government involvement.