My main reason for asking is based on the behavior and actions of Russia and Putin if a referendum (or any type of legal election) by the people of a certain area is successful (without going into the legitimately of the actual referendum) then they will approve it and back it.
Did you read the link in the first response to your post?
You got it completely backwards from what actually happened.
"
Alone among European powers Russia offered rhetorical support for the Union, largely due to the view that the U.S. served as a counterbalance to the British Empire.[16]"
France and Britain wanted a divided USA. Russia wanted a counter balance to the power of Britain.
As others have said, it all boils down to leaders doing what (they believe) is in their countries interests at the time. It should be no surprise that Putin puts Russia's interests first and foremost.
If you want to know why he is doing the things he is doing, find out what Russia's interests are.
This video will give you 100x more information on Russia's motivations for exercising control over certain geographical regions than you'll ever get on these forums.
https://www.youtube.com/watch?v=HE6rSljTwdU