The 10th Amendment does not allow the States to ignore or violate the Constitution as a whole. But, the problem now is that the Feds are equating a lifestyle choice with an immutable characteristic such as skin color. If this stands, the proponents of most any aberrant sexual behavior will make the same arguments to try to force states to allow said behavior.
The Tenth Amendment expressly states that any power not delegated to the feds or prohibited from the states is reserved to the states and the people.
You have to understand that the Constitution is mainly pointed at and is a limitation on the federal government. If it is not an enumerated power delegated to the federal government by the states and the people via the Constitution, then it is not a valid federal power.
The issue here is whether the Constitution has delegated power to the feds to interfere with marriage. The answer is NO! Nowhere does the Constitution delegate an enumerated power to the feds that allows them to interfere with marriage. Therefore, the states are free to reject and nullify such unconstitutional federal acts.
What does “immutable” have to do with anything? We don’t (for example) say that it’s OK to discriminate against Jews because they could always convert to Christianity if they get tired of being discriminated against.