"if Nicholas had never married Alexandra then the Russian revolution would never have happened." the beginnings of the revolution started during the reign of Alexander Pavlovich (1801-1825), when he and his army went to Paris after the defeat of Napoleon. some of the officers came back influenced by the ideas of democracy etc, and so the seeds of the revolutionary movement were sown. most of the groundwork for the revolution was done before the reign of Nikolai Alexandrovich, so no matter who he married the revolution would have occurred anyway.
Russia did not need another social butterfly like Maria Fyodorovna, she needed an Empress that the people could connect to and look to for guidance. the social and financial extravagance of Maria Fyodorovna I'm sure did not endear her to many ordinary Russians.
Alexandra Fyodorovna's 'fascination' with Rasputin is understandable and justified, even if it wasn't back then. she did not 'bully' Nikolai Alexandrovich into making decisions concerning government, she made them herself. even when she expressed opinions about matters that the Tsar had control over, it was not often that he heeded her advice.
the reclusivness of the imperial family was apparent even before the birth of Alexei Nikolaevich so you cannot blame Alexandra Fyodorovna for that. and even if Nikolai Alexandrovich had married Helene of France, how do you that she would not have produced many more daughters and no sons at all?
blame for the end of the Romanov dynasty ultimately falls into the hands of Nikolai Alexandrovich, a Tsar totally unsuited to ruling Russia, given his upbringing, personality and various beliefs.
Russia would have never won the war. full stop. i think this one needs no explaining.
and even if Russia had won the war and the revolution never happened, how do you know that everything would have been peachy from then on. it's just like saying that if Hitler had been killed in world war one then the fascism of Italy and Germany would have never happened. far worse dictators and tyrants could have emerged (although it is hard to imagine)
and finally, have you ever read up on communism for yourself? read the works of Marx, Lenin, Engels, etc and assembled your thoughts instead of re-iterating the capitalist American propaganda that is constantly shoved down our throats?