It was entirely logical and normal for a government of a great power to punish a next door neighbour for siding with a nuclear armed enemy, as history has shown. And Russia had been saying for years that Ukraine joining NATO was a bright red line that was not to be crossed or else: there is no point in making an ultimatum that won't be carried out. (This applies in all relationships of course).
What was unpredictable was what Russia did after the initial regime change attempt failed. Who knows why that happened.
