It's everyday business and it's usual, it's a professional relationship between first officer and Captain, and it's a a loyal friendship between Kirk and Spock. And of course it's a love affair! It's just so natural the both don't have to boast about it.

Did you really believe the hugs they shared in public were less than a foreplay? That the looks Kirk shot Spock's butt on the bridge were merely saying: "Strange Vulcan, kinda funny, what's for dinner?" That Spock meant to say after the Pon farr incidents on Vulcan, when he was back on the ship and grabbed Kirk's shoulders with his first public smile ever, simply struck by the feeling of gladness that Jim was alive, did you really think the only thing going on in his head was: "It's good that he's alive. Now I gonna check some star data"? You could have known by then latest: In truth they were warm and comforting hugs, consoling and stabilizing, their looks were saying: I wanna grab that apple tush. And Spock's grip was saying: I don't want to be without you.

Both of them are used to pursue thoroughly what irritates them, they deserve their posts on the Federations flag ship because they do everything to completely clear all questions. They aren't satisfied with a superstitious answer. Once there interest is caught they find out about their subject of interest for good. And they did catch each others interest. Who after all would be more interesting than the next in the line of command, a man equal to the other in knowledge and sharpness, in curiosity and determination? It was overdue that they pursued each other thoroughly. Bones told Jim to do it again and again.