All Marriage Is UnConstitutional
In the United States, there are more than 1000 laws - some federal and some state - that provide married people with rights and benefits disfavors unmarried citizens.
At the foundation of our constitution, there will be no discrimination on the basis of age, sex, religion, or heritage(color). This seems pretty straight forward. We will not have laws that create a disfavored class of people.
Individuals are citizens of the United States, regardless of marriage, size of your family, etc. However, our Senators and Representatives have passed laws that create disfavored classes by offering benefits and tax schemes that create disfavored classes. Married people get the right to either file jointly or as individuals - whichever serves them best. People with children get tax benefits. These laws are unconstitutional. They favor a class of people over another.
If the Supreme Court wants to clean up the books, they should rule that all marriage laws are unconstitutional because they lead to making single people "disfavored."