I think Number One is supposed to be Pike’s friend and confidant, similar to Sisko and Dax’s relationship in DS9.
Who else is he going to confide in on this matter. Spock giving Pike relationship advice would be pretty wack.
Spock: Captain, I could not help but notice that the USS Cayuga warped away sooner than expected given your relationship with Captain Batel. The crew assumed you would want some “alone time” as ensign Uhura put it. I will not repeat what lieutenant Ortegas said. Pike: Wait, you guys talk about my love life on the bridge? Spock: Indeed. It is a matter of some interest. Pike: Okay, I’m not exactly comfortable with that. Spock: Captain, if you and Captain Batel are experiencing…difficulties, I would be happy to demonstrate some neuro-pressure massage techniques which can be quite stimulating. T’Pring has said I am particularly skilled, and as you are aware, Vulcans cannot lie. Pike: Okay, now I’m really uncomfortable with this.
I suppose Doctor M’Benga could sub in as confidant instead.