It was the small details that any couple would notice. Small things they did that the other partner was neither for or against. But, they noticed. How could they not?
The fact you usually made Spock sleep in your bed when you two slept together because you simply preferred it, the fact a blanket was now always on his bed for your comfort. The way your room now had various objects such as statues instead of just the photos on the walls. Books and clothes lived in both their original place and in the other's room. Very soon your shelf had more books in Vulcan than in English, vice versa for Spock.
Schedules were swapped around as much as possible so a few hours at least could be spent sleeping with the other. Most of the time it was simple sleep while being next to the other. Very few times it was anything else, but when it was, it couldn't have been sweeter.
You two were in what various members of the crew called 'beginning bliss', 'the flame before someone blows it out', and McCoy's personal favourite of 'heaven before hell'. He'd then start cursing out his ex-wife or Vulcans in general. Honestly, sometimes you felt that he had been married to Spock and still was.
"Something is on your mind,"
It was a line spoken without a hint of a question. Someone sat next to you and followed your gaze. Right to the Vulcan harp placed prominently on a counter top, leaning on a wall divider.
"Will you play for me?"
"If you wish-"
"Bridge to commander Spock."
Spock felt a light kiss on his cheek before you stood up and went to find something in the far end of the room, giving him some privacy. He clicked the com and spoke in his usual monotone form.
"What is it, Captain?"
"We need you on the bridge."
The words were stopped by your fingers brushing against his, lips on his. He slowly placed a hand behind your head and kissed you a bit more deeply, his hand firmly grabbing hold of yours.
He the pulled away, and you let his lips and hands slip away as he stepped back and turned. He straightened up, but his arms behind his back and went towards his door. He did glance back though, as he always seemed to do. He didn't even know why he did it himself, but he started one day and never stopped. A kiss and to look back. No words had to be exchanged. Especially not after he saw your pleased look before he did indeed, leave for the bridge.