An interesting thought puzzle . . . certainly not amenable to any certain answers, but fun to try to assemble nonetheless.
First, let's start with what we know about the relationship that did exist. Alexander III had not initially been a proponent of the marriage between Nicholas and Alexandra. (Why this was so has been discussed extensively elsewhere. My own view is that her coming from a family in which hemophilia was known to pass through the female line had a lot to do with it.) But he eventually came around to accept it, probably in part because it was the first spark of determination to stand his ground that he had ever seen from his son.
No matter what his real reasons were for first resisting and then relenting, Alexander no doubt was poised to welcome Alexandra into Russia as an inevitability rather than as an ideal future empress.
From her end, Alexandra respected her grandmother's opinion, which held that Alexander III was a posturing boor who was ruling with an unnecessarily harsh hand over a backward country that, just under the surface, was on the boil politically . . . and whose foreign policy bore no particular goodwill for English interests.
So whatever views Alexandra eventually would develop of Alexander -- and how those views would interplay with and affect the views he developed of her -- would certainly have sprung from inauspicious beginnings on both sides.
Personally, I do not think their views would have ever comfortably melded. While Alexandra and Alexander shared a superficial desire for a certain remove from public life, it was driven by two very different motives. Alexandra was almost pathologically shy, not physically up to the stress of imperial social engagements, and profoundly domestic in her tastes and habits. She would have sought a reserved life in almost any social stratum in which she found herself. Alexander's removing himself from St. Petersburg had more to do with the physical security of himself and his family. While he was not personally inclined to the lifestyle of the St. Petersburg fast set, he was quite willing to traffic with that crowd on the terms he set. (Hence his indulging his wife with some of the social whirl in which she revelled, while putting an end to each event in his own unique way when he was ready.) And, no matter what his personal preferences, he never would have risked the isolation of the ruling house from the upper social and military classes on which it depended for support.
He also had an unbending sense of duty. Whereas Alexandra built a cozy and self-consciously-middle-class nest for her family at Tsarskoe Selo, Alexander imposed simplicity on his family almost as a matter of military discipline -- a view that self-denial and hardship built character in a tsar and his heir.
Alexander managed to remove himself physically from the center of St. Petersburg without isolating himself intellectually and emotionally from his nation. While we may not like his policies, they were set with a clear view to the political and social situation in Russia. (While the long-term effects of his policies might have deepened the radicalism of some elements in Russia, they at least managed to turn the larger political tide for a time and engender centrist support for the monarchy. Nothing Nicholas ever did turned any political tide for any length of time.)
Alexandra's cocooning of herself in Tsarkoye Selo was but the outward manifestation of a deep-seated drive to build a fantasy world in which she could stay emotionally afloat. In that world, the Russian peasants were the God-fearing, Tsar-worshipping children she wished them to be. The Romanovs who pressed Nicholas to accept reforms were the effete, self-serving, untowardly ambitious connivers she thought them to be. The ministers who challenged Nicholas' views or tried to bolster his resolve against her inclinations were the traitors she knew they must be to question their Tsar.
Had she been empress-in-waiting during the continuing reign of Alexander, she might well not have become the ultra-monarchist she became with her husband. The political heritage in which Alexandra was raised was at odds with Russian autocracy. Alexander had the strength to rule, which created a safety zone in which his methods and heavy hand could be questioned without risking the monarchy itself. Had she not been dealing with a husband of notorious irresolution on key matters, to which she responded by becoming the cheerleader for absolutist rule, the more liberal strains in her background might have come more to the fore. (While the evidence is contradictory, there are at least some indications that Alexandra had occasional bursts of liberal outlook regarding, for instance, the Jews.) In other words, Alexandra's far-right leanings might have been more a response to Nicholas' weakness rather than a natural bent that would have cozied her up to Alexander politically had he remained Tsar.
I do believe Alexandra would have benefitted by "interning" under Alexander and Marie for a while before being thrust center stage. But, ultimately, I believe she and Alexander were two very different streams that never would have had any real confluence.
