Hey, here's a thought for kicking over the chess board:
The Nexus is supposed to let you live your deepest fantasies. What are Kirk's? I suggest he's happiest when he's being Torn between Duty and His Life. He falls into depressive fits about this in ``Balance of Terror'', in ``The Ultimate Computer'', in The Motion Picture, in The Wrath of Khan. There's touches of it in ``Shore Leave'', in ``The Paradise Syndrome'' ... all over the place, really.
So what does the Nexus give Kirk? The fantasy of being torn between his private life and the lover he can't ever have (note that she's never where he can even see her clearly!), versus the call of duty wanting him back. It's not Antonia he wants; it's the experience of being torn between Antonia and Enterprise!
No, I don't buy it either; honestly, all things considered, I'd rather we disregarded the ``78 Years Later'' tag for the people who do insist on working out detailed chronologies, since the chronologies work much more easily and sensibly when there's more ambiguity in the timing.