There was a vote, the people of Crimea voted to be free of Ukraine and the EU. They wanted their language and their church. If Russia invaded, the family members visiting their relatives under the Ukranian thumb. They had to protect the vote. I don't believe you have a clear idea of just how much the people of Crimea despised the EU. Have you ever spoken to one? They were arrested for speaking Russian. Their children were not allowed to speak Russian in school. Their churches were burned to the ground. If Ukraine tries to take back Crimea, it will be one of the bloodiest civil wars in history.