Well, ... not quite.
The Supremacy Clause coupled with the 14th and other Amendments sorta makes Federal Law binding on the States. It was not always that way nor was it intended by the Founders to be that way but it is what it is today. The Supreme Court can and has determined Gay Marriage Rights are NOT a Federal Question and that defers to the States... I think the current control is Nelson v Minn...
Now... the Federal Marriage Act, DOMA seems to violate a few provisions of the Constitution (as interpreted) So I expect that to be overturned. Prop 8 in California ought not be 'forced' on the other States because in that issue Gay Folks had the right that the Prop took away.... Because the Strict Scrutiny level is applicable (Fundamental Right of a Suspect Class) to do so and the State nor the Prop folks met that standard or even close I expect the USSC to sustain the Federal District Court and the 9th Circuit.
Where did you hear this. I think you are heavily confused what your constituion does. The U.S. federal Constitution was designed to provide various structural limitations on federal power. Your Constitution established a federal government of limited and enumerated powers and it vertically created a separation of powers between state and your federal government. Your constitution prevents your government to interfere with state law because they are unjust. Why you think its such a issue?