Not necessarily. They formed an alliance which is legal under both countries' documents of sovereignty.
An example:
Most E.U. member countries relinquish the protection of their borders to the E.U. organization proper. Does it lessen the sovereignty of the country? Yes,for instance, because of that reason France didn't acquiesce to the E.U. and retains full sovereignty and their own military.
Is it treason? No, because they have defined treason to allow it.
Yeah, but the E.U. contracts are out in the open (not secret) and the people had to vote for Germany to become a member of the E.U. At least in Austria we had to vote, I think it was the same in Germany.
