"You perhaps believe the Constitution has no more meaning than an Islamic wedding?"
I believe secession was specifically addressed and allowed.
Not only do you believe incorrectly but you cannot find a single statement in the Constitution, in the Ratifying Conventions documents, in the writings of the Founders or in the logic of a Constitution which supports your incorrect view.
In FACT, the idea was explicitly rejected by Madison in a letter to Hamilton during the NY state convention. Once in the Union, always in the Union was what he said. Thus, the attempt to produce a "conditional" ratification with the possibility of future withdrawal was rejected.