Bubble Bath
Spock hates the water, she thinks; and - after considering the reasons why this would be true - she understands.
After two long sweaty days on a dusty world, she tries to talk to him about bubble baths. His brow crinkles, just the tiniest bit, and he tilts his head as he looks at her.
He understands immersion.
He understands 'the universal solvent', and the function of soap; he understands the effects of various factors involved upon the human nervous system; he even understands the beauty of the ephemeral translucent spheroids. And while he acknowledges that his mother enjoyed this combination also, he simply does not see the attraction; and so he says nothing.
Nyota tells him about this 'bubble bath', and watching her face, he nods: He recognizes that it appeals to her sensual nature. He hears the faint note of yearning in her voice, and knows that this is a comfort of home that neither he, nor the Enterprise, can provide.
A bubble bath does not make sense.
On evenings when he is working late, she sometimes takes her reading to the pool deck. She changes into a swimsuit, and sits on the edge reading, her feet dangling in the water. When the call of the cool blue becomes too much, she takes her padd to a waiting chair. She pulls out the band that holds back her hair, drops it onto the padd. She shakes her hair down around her shoulders, feeling it sweep across her bare skin. Walking to the end of the waiting lane, she realizes that this is now the only time she does this, feels this, outside of his quarters, or hers: It is an unconscious gift she has given to him – Her hair, loose and framing her face, is something only he sees.
She understands immersion.
She stands, for a moment, right on the edge, with her toes curling over – and then she dives.