Ah, welcome to the muddied waters of 40 years of canon and continuity.
On prearranged marriages and dating.
Perhaps it is the 'upper crust' of Vulcan society that participate in prearranged marriages. One could argue, due to his contacts and influence, that Sarek most likely comes from privilege. He himself was likely betrothed (as mentioned by Pavonis) due to the retconning in ST V, by introducing Spock's older half brother Sybok. Though never mentioned before, or ever-after, who was Sybok's mother and what happened to her? Sarek must not been that attached to her, or to Sybok for that matter, because the only people he cried out for in his last hours as the Bendii syndrome was taking him was Perrin, Amanda, and Spock. So after Sarek's first wife is out of the picture, he obviously must have first dated Amanda, and then later on Perrin.
We know from Amok Time, that Spock was betrothed to T'Pring, but that when his Pon-Far pulled him back to Vulcan, T'Pring rejected him, instead choosing Zonn. Dating? Not sure. Coupled? Yes, they seemed quite close.
Now here is where things get murky and make me wonder if prearranged marriages are just for the upper class. There is no indication what so ever that Saavik was ever betrothed. If we are to believe what was not so subtlety hinted at in ST III, she helped the reborn Spock through Pon-Far, time and again. Taking it another step, there is much speculation that she was pregnant with Spock's child in ST IV and later married him, as hinted at in TNG's Sarek.
So as I said. There is nothing concrete one way or the other.