The existing relationship in Star Trek: Strange New Worlds between Captain Pike (Anson Mount) and T'Pring (Gia Sandhu) creates a mystery about why Spock (Leonard Nimoy) never told Kirk (William Shatner) about his fiancée. In Star Trek: The Original Series it was revealed that Spock had been betrothed to T'Pring since they were both seven years old, but it's clear that Kirk was not previously aware of her existence. Interestingly, Nurse Chapel (Majel Barratt) also appears shocked when T'Pring appears in Strange New Worlds season 2, episode 1, "Amok Time," but this could be explained by the fact she's always known her as Spock's fiancée, rather than as his wife, which is how Spock identifies her in Star Trek: The Original Series.
"Amok Time" is a hugely important moment in Kirk and Spock's friendship, as the Vulcan requests Jim's presence on his home world to observe the koon-ut-kal-if-fee ritual, in which Spock must fight to the death to win the "possession" of his wife. T'Pring chose Kirk as her champion, a calculated move to win her desired mate, Stonn, that put the Enterprise captain's life at risk. Believing that he's killed his friend, Spock prepared to hand himself over to Starfleet authorities but was overjoyed to discover that Doctor McCoy (DeForest Kelly) had faked Kirk's death. It was a rare display of emotion for Spock that highlights his close friendship with Kirk. However, it creates a mystery as to why Spock told Pike about T'Pring but not Kirk?
What We Know So Far About Pike's Friendship With T'Pring
In Star Trek: Strange New Worlds season 1, episode 1, Pike heads out to rescue the Enterprise's Number One from a first- mission gone wrong. Calling Spock back to the Enterprise, he finds the Vulcan in bed with T'Pring. Over the course of his conversation with the couple, T'Pring refers to Pike as "Chris", suggesting that they know each other relatively well. Not much more information has been forthcoming on how Pike and T'Pring know each other, but the answer could lie in Spock's experiences during Star Trek: Discovery season 2. After encountering the Red Angel, Spock committed himself to a psychiatric facility, experiencing emotional dissociation and a deficit of empathy.
In Strange New Worlds, T'Pring works as of a Vulcan rehabilitation facility, which houses Spock's Vulcan half-brother Sybok. The facility specializes in treating Vulcans who have lost control of their emotions, so it would stand to reason that Pike could have come into with T'Pring during Spock's time at Starbase 5. Spock requested that Starfleet not inform his family, but this instruction wouldn't technically include his bethrothed, T'Pring who herself has experience with Vulcan emotions.
Why Spock Didn't Tell Kirk About T'Pring Until "Amok Time"
Pike s Spock and T'Pring in 2259 which, depending on the exact dates, is about seven years before the events of "Amok Time". Vulcans only mate once every seven years, and this mating period, Pon Farr, is supposed to be private. Spock's choice in "Amok Time" to tell Kirk about this deeply personal aspect of Vulcan biology is driven by the fact that he will die if he doesn't return home to mate with T'Pring. It's an exceptional circumstance, like the Red Angel, which may have introduced Pike to T'Pring a decade earlier.
Given his impending arrival in Star Trek: Strange New Worlds season 2, it is strange that Kirk was unaware of T'Pring's existence up until 2267. Spock's story in the Star Trek prequel has been focused on his struggle with his human and Vulcan aspects, creating a love triangle with T'Pring and Nurse Chapel. It's therefore likely that Spock's reluctance to mention T'Pring to Kirk is a side effect of rejecting his humanity in favor of the privacy and emotional stoicism of his Vulcan heritage.