Antonia was a love interest of Starfleet captain James T. Kirk, whom he met in 2282 while horseback riding near his uncle's farm in Idaho. Despite having fallen in love with Antonia, Kirk ultimately chose to break off the relationship, choosing instead to return to his career in Starfleet.
In 2293, upon being pulled into the extradimensional realm known as "the Nexus," Kirk experienced a reality in which he was given the chance to change history, and chose to propose marriage to Antonia instead of leaving her. Later, he relived the day on which he initially met Antonia. Although these experiences initially led Kirk to choose to remain in the Nexus, seeing it as his opportunity to correct the mistakes of his past, he ultimately chose to leave upon realizing that the events he was experiencing were not, in fact, real, but rather an elaborate illusion. (Star Trek Generations)