the premise (tip of an axiom)
And time is the fourth. And space is the third.
And Spock will be dissatisfied in all of them, forever.
Spock has accepted, for some time now, that what Jim admires about him is at least partially tied to his exoticism. The fact of him as a being of Vulcan; the fact of him as being not quite of Vulcan and thus alien to Vulcan as well; the fact of him as possessing of an experience adjacent to humanity.
Jim does not do this with ill intentions. He does not show his love to Spock, as ever he does such a thing, in a way discreditable to a Starfleet captain whose respect projects for each and every race and culture encountered, though some adjustment time is usually necessary for those peoples whose customs and expectations are more distinctly removed from a traditional Earth human's.
But, however this truth of Jim's makes itself up, Spock has grown accustomed to it. Perhaps, he has even begun to take it for granted. He is assured some type of security, whether platonic or romantic or - much more likely - some more applicable space lurking between, toward a position in Jim's consideration; in his mind, in his heart; because of his status as Spock, the unknowable, the immeasurable, the non-quantifiable, the impossible.
So it stands to reason that Jim should not be half so at home as he is, in this distant era of a bygone New York. Jim should not love Edith as he does. Jim should not be so fluid to this strange normalcy.
Spock is not jealous. Spock is simply logical.
When he lids his eyes and rests, sitting upright or nearly, at his workstation, he imagines the pricks of stars at the tips of his ears, those unassailable signals that you could not find someone so wonderful as Spock with an instrument so mundane as a rice picker. If Spock had a rice picker, it would be gilded in platinum, in the midst of humanity's Great Depression.
This is no new revelation. Not that Spock is alien, neither that Jim is bound by love and curiosity, an all-consuming loving curiosity that unfortunately defies logic, to most every landmark in their universe.
And so, again. Jim need not apologize.
But Spock, unfortunately, cannot accept that. Spock wishes, with Jim's hands on his shoulders and Jim's lips ghosting his ears, that he would.