Did it take a hit when interracial marriage became legal or allowed woman to vote or overturned slavery? I don't really see the difference. But if you say so......
If you can't see the difference, then any answer I give you will be meaningless. But here ya go, anyway.
Interracial marriage was about equal protection under the law. It did not redefine what marriage actually was, and still left the definition of marriage up to the states. So no, neither Democracy nor the Constitution took a hit on that one. Racism took a pretty hard blow, though.
The Supreme Court flatly voted against women having the right to vote, several times, leaving the voting requirements to the states, where the Constitution says it belongs. Women gained the right to vote when the states got together and ratified a Constitutional Amendment to allow women the right to vote. Both the Constitution and Democracy were strengthened that day, not weakened.
When slavery was overturned, the Constitution took a severe hit because it set the precedent for the federal government to usurp states rights, a precedent they have abused over and over again since then, including today. Democracy, on the other hand, took a giant leap forward. Democracy could have easily overturned slavery, and it was about to, which is one of the reasons the slavery states started talking succession.
Today, as Supreme Court Chief Justice John Roberts noted in his dissent,
"Five lawyers have closed the debate and enacted their own vision of marriage as a matter of constitutional law." They took away from the states the ability to define marriage, something the Constitution does not give The Court the right to do, so the Constitution took a hit today. And as Justice Antonin Scalia said in a scathing dissent, the decision shows The Court is, for the first time in history, a very real
"threat to American democracy." Said the ruling
"says that my ruler and the ruler of 320 million Americans coast-to-coast is a majority of the nine lawyers on the Supreme Court." So Democracy took a major hit today.