>>>Government couldn’t “discriminate” if they got out of the marriage business, but that makes too much sense.<<<
Government is not in the “marriage business”. For centuries, governments have almost universally recognized that the natural order of things is marriage between one man and one woman.
Recognizing that a special and unique relationship exists between a husband and wife, goverments have passed various laws that allow the man and wife to basically be treated as one entity, for certain purposes. Government only licenses marriage, in order to keep track of who is married to whom, and who is subject to the legal benefits and responsibilites of marriage.
Why is it necessary for the government to license marriage or any other relationship? People are married civilly, how are they not in the business. Siblings can live together, support each other and bequeath property to the other, but they don’t need a license.
Just because the government recognizes order as your see it and “has your best interest at heart” doesn’t mean they should be involved in the slightest.