[Spock regards Jim...
As much as he wants to tell Jim everything, it's difficult to do so. Maybe they weren't ready.]

Jim, you are my T'hy'la... nothing will change that. If this was known to me outside of Luceti, I would not be with Nyota.
[Though they were friends, neither of them had any romantic inclinations because Spock had Uhura, and Jim.. well... there was Carol to consider.]