My mentor on this subject is James Madison, whose words I quoted immediately after the Virginia ratification.
In Madison's formulation, "mutual consent" to disunion is the moral equivalent of "oppression" or "usurpations" which are a "violation of the compact as absolves them from its obligations."
But there were no -- zero, zip, nada, none -- "usurpations" "oppression" or "injuries" in November 1860, just days after Lincoln's election and four months before his inauguration, when South Carolina slave-holders first began organizing to declare their secession.
That made their declarations neither "mutual consent" nor from "violations of the compact" of which Madison approved, but rather disunion "at pleasure" of which he did not.
Lot of words - but you avoided answering...Why?
So is it your position that under *some* circumstances Virginia *has* the right to unilaterally secede?
(Has not had)