Actually, I cannot think of a single example of any sub-region or colony wishing to “amicably divorce” EVER having been allowed to leave peacefully. Killing and misery have always been part of the deal, because those in power never ever ever want to give up any significant portion of that control.
Depends. Generally secession is associated with bitterness and anger -- taking back one's "rights" from the "oppressor."
Secession isn't usually attempted in a calm and peaceable spirit of respect for the country one's leaving. Consequently it's no surprise that secession attempts are met with anger and resentment from those who are cast in the role of the "oppressor" in some narcissistic drama.
When separatist movements take a more peaceful route and ask for consent from the rest of the country and don't regard their fellow countrymen as evil oppressors they may meet with more respect and consideration from the other side.