Spock took it personally that his performance leading the Geology department had been less than exemplary. That he had not been allowed to rectify his error rankled the Vulcan perfectionist even more. Kirk's quiet changes - without consulting his valued first officer - layered irritation into the emotional mood sandwich.
Spock sulked.
Even Uhura had never seen a Vulcan sulk before.
Spock pouted.
Not in an obvious or human way.
But Uhura noted the ever so slight protrusion of his lower lip in an amusing Vulcan imitation of her own pout. Suggesting to Spock that he acknowledge his feelings only brought down a frown to accompany the pout.
Clueless Kirk queried McCoy about Spock's new facial expression, exposing another opportunity for the good doctor to get under Spock's Vulcan skin.
McCoy, in his unending quest to find creative ways to annoy Spock, forced him into Sickbay- citing "Captain's orders" - to check on the newly evident "facial paralysis" making Spock's lower lip sag outward. After two hours of fun, as McCoy ruled out everything from a brain tumor to Bell's Palsy, he released Spock back to active duty with a diagnosis of "Almost Human".
After McCoy's "exam", Spock stopped speaking to Kirk in all but a professional capacity.
Uhura's attempt to mediate the relationship challenge met with two almost intractable issues - Kirk and Spock.
Kirk, never known for his patience with interpersonal relationship issues (except with Uhura and Grayson), could not for the life of him understand Spock's problem. After all, in Kirk's mind this had all been done for Spock and his family - to keep them where he knew they wanted to be (being Kirk, he never actually asked them if they wanted to raise their kids on the Enterprise).
Spock became uber-Vulcan and denied there was a problem as a relationship issue would involve emotions and he, as a mature Vulcan, had complete control over his emotions. At all times. Except during intimate relations with Uhura as she "expressed a preference for more passionate and uncontrolled sexual congress."
Frustrated beyond endurance with both of them, she grabbed each of them at the next starbase and forced them into a bar. She ordered drinks (with chocolate for Spock) until massive amounts of control was lost, then she injected the topic they needed to discuss. Once they started arguing, she rose and navigated her slightly tipsy self back to their temporary quarters to relieve her favorite babysitter, Pavel the Adorable.
When they regained consciousness, Spock and Kirk were once again the Dynamic Duo.
Her plan worked.
It worked really well, she'd admitted to Carol and Soo-yee.
Waaaay too well.
Because from that point on, Jim Kirk scheduled "interpersonal discussions to improve male officer cohesion and communications" at every starbase they docked with and on every planet they orbited.
Kirk and Spock were now joined by McCoy, Scotty and Sulu - Chekov remained under the drinking age at most (but not all) of their meeting locations.
Having observed Uhura ordering drinks for Spock at the ice breaker, Kirk enjoyed the fact that he now knew how to get his first officer drunk off his ass - making sure the bartender got tipped in direct proportion to the chocolate in Spock's drink.
Kirk's "club" was fast developing a reputation throughout Federation space.