It was definately an issue over Federation relations with the Cardassians that seems to be at least one root of the issues between Sarek and Spock. Consider that was only maybe twenty or thirty years prior to Sarek's death (unless the Federation has been taking issue with the Cardassians well before the 2340s, like say with the occupation of Bajor in the 2320s). So they were probably not estranged for many years, though I imagine Spock and Sarek would have issues after Amanda's death.
Picard went to Sarek's son's wedding at somepoint prior to Sarek and Spock's second estrangement. Since Picard has also met Spock once before, one can assume this was the same time (meaning Spock's wedding). And that it was definately not Spock's wedding to T'Pring, since not only was Picard not born yet, but Spock and Sarek were not speaking yet (that was before the Babel Conference). Sybok is assumed dead, and Sarek is not known to have any other sons. None with Perrin is known to have been born. And the giant clone "Spock 2" probably is out of the question.
Picard went to Sarek's son's wedding at somepoint prior to Sarek and Spock's second estrangement. Since Picard has also met Spock once before, one can assume this was the same time (meaning Spock's wedding). And that it was definately not Spock's wedding to T'Pring, since not only was Picard not born yet, but Spock and Sarek were not speaking yet (that was before the Babel Conference). Sybok is assumed dead, and Sarek is not known to have any other sons. None with Perrin is known to have been born. And the giant clone "Spock 2" probably is out of the question.