I do not know all the details. It the fog of war is still thick. States do not secede unless they are in an irreconcilable situation. When their President was overthrown and their language outlawed, they saw the writing on the wall. The Obama administration’s overthrow of Ukrainian Democracy, like the overthrow of undemocratic Libya, Syria, and Egypt, has resulted is mass death and disenfranchisement.
True... much of LDR and DDR did attempt to secede, but you seemed to be referring to the entire region which is now occupied by Russia, which is far, far larger than the portions of LDR and DDR which seceded.