Not usually.
I think that in this case, the problem is threefold:
1) Your regions were very fond of the SA realms.
2) All the realms declared war on you together.
3) The secession.
Well, our regions were not "fond" of S.A. they were if anything room temperature, they had no reason to be fond of S.A.
And your second point merely compounds mine that if you mass declare at one time, you can take down a realm just through using war protest coding.
