If you want to make a constitutional argument, you have to present the clause of the constitution that grants the government the power to regulate/prohibit consensual interpersonal relationships.
If there is no power granted in the constitution, then the law is unconstitutional.
It is a state law issue and always should have been. It should have never been a federal issue to begin with.
I suppose you are going to tell me that states have to get their power to regulate from the federal constitution?
Why all the fear of the states and the people?