[Non-Sequitur]

In seceding, a state neither forms a new Sate nor forms or erects a State within the Jurisdiction of any other State.

In seceding unilaterally, a state removes itself from the Union and changes it's status without consent of Congress. Since Congressional approval is necessary for every other change in status then by implication it should be required for leaving as well.

In seceding, a state does not enter into any Treaty, Alliance, or Confederation, etc., etc., etc.

In seceding unilaterally, a state is taking an action which may have a negative impact on the interests of another state. Since Congressional approval is required for other actions by the states which may have a negative impact on the interests of the other states then by implication it should be required for leaving as well.

[nolu chan]

Since Congressional approval is necessary for every other change in status then by implication then it should be required for leaving as well.

Then the Constitution does not "make it clear" but rather "implies" that "it should be required" for leaving, per your reading.

Since Congressional approval is required for other actions by the states which may have a negative impact on the interests of the other states then by implication it should be required for leaving as well.

Then the Constitution does not "make it clear" but rather "implies" there "should be" such a requirement, per your reading.

Others read what is actually stated, do not imply what is not there, and reach a different conclusion.