I don’t know why the Supreme Court is examining marriage equality except that it is PC for activist justices to be able to do so. After all, if parents were making sure that their children were being taught the Constitution as the Founding States had intended for it to be understood, particularly the division of federal and state government powers, then schoolchildren would be able to tell us that Founding States made the 10th Amendment to clarify that Constitution’s silence about issues like marriage, abortion and healthcare make such issues state power issues.
The Supreme Court is examining “marriage equality” because lower court liberal judges have imposed same-sex marriage, and the appeals process leads to the Supreme Court.
Also, though marriage and family law are normally dealt with at the state level, not federal, the Defense of Marriage Act is a federal law on the subject of defining marriage. So, it was inevitable that the Supreme Court take this up at some point, since the homosexual activists decided years ago to try to force this through the courts.