And after that Crimean people expressed that they don't like that by voting out of it.
Regarding referendum, it's results (95-96% vote for independence) are obviously falsified. There is nothing new: in 1938 Hitler also got 98-99% votes in occupied Austria [1]. Those 95% in Crimea as real as Hitler's.
[1] https://en.wikipedia.org/wiki/Austrian_Anschluss_referendum,...
Let's take a look at the ethnic groups in Crimea - 2014 census:
Russians - 65%
Ukrainians - 15%
Crimean Tatars - 11%
Please note that, of the 15% of Ukrainians living there, most (60%) speak Russian as their first language.
We may argue if the 97% referendum result was rigged or not - we may never know.
But based on the above numbers I think that the people in Crimea really prefer to be part of Russia - because they are Russian!