Spock deeply, passionately, madly loves Nyota. This is significant not only in respect to their relationship, but because Vulcans are not known to do anything deeply, passionately, or madly. The largely human crew of the Enterprise have long since figured out that he does have feelings, but his father's culture (his own?) flip flop between seeing him as a raging, emotional fool and a miracle man who overcame his mother's influence to achieve a lack of feeling.
The truth is, Spock is neither an emotional fool or a miracle man. It took him years to realize it, but the struggle between the two worlds need not be a struggle at all.
"Mr. Spock, we have never had a Vulcan apply to Starfleet before. I'm curious: do you anticipate any difficulties fitting in socially?" The admissions officer leaned forward, unashamed at his illogical question. The purpose of Starfleet was not to socialize, it was to help the Federation.
"No I do not. My mother was human and she did her best to teach me her culture's customs. I have experienced the wisdom of my father's people, now I wish to learn from my mother's home world."
The admissions officer smiled, just a bit. "A very wise and, may I say, logical, answer."
For his entire duration as a cadet, every decision he makes proves that answer to be a lie. Everything is clinically logical to the point where his roommate takes to walking around naked just to get a response out of him. His seeming lack of emotion continues into his stint as an instructor and up to the point where he meets Nyota.
He'd like to say their relationship is based on logic, that she was the obvious choice for him to start a relationship.
But the truth is he loves her and can't get enough of her.
Fin.
Author's notes: I ship this pairing so hard it makes the Titanic look like a bath toy. OTP.