Two simple "Motivationals" about Kirk and Spock dragged seemingly randomly off the web. But they say everything there is to say about Spock/Kirk in a nutshell.
Point 1. It was written into the script by the Author. This is not some stuff dreamed up by a load of numpties on the 'net. This is all FROM CANON. From TEXT, from SCRIPT. From THE HORSE'S MOUTH.
Point 2. As extended over the Original Movies, this is High Drama and probably THE GREATEST LOVE STORY EVER TOLD.