And just because Spock couldn't put his arms around Kalomi in an affectionate manner doesn't mean he wasn't banging her.
I'd think that this line you passed over heavily implies that that is not the case:
LEILA: Mister Spock's feelings were never expressed to me. It is said he has none to give.
Folks seem to forget Spock went through quite a metamorphosis between The Cage (which was roughly a decade earlier) and who he was during the five-year mission.
That's because that clip is from the unaired pilot (later reworked into The Menagerie), in which Majel Barett's 'Number One' is supposed to be the logical, unfeeling character, not Spock. I think the viewer is just supposed to pretend that Spock isn't smiling in that scene.