unless 'when everyone was together' you mean all her lecturers, the vice chancellor, the rest of her graduating class and their families, presumably none of whom give a fuck about them marrying, that's no excuse to do it actually at the ceremony - he could have done it before or after; during photos; most people go for a celebratory meal, etc. If the families were travelling from abroad it's highly unlikely they would literally only stay in the country for the 2 hours of the ceremony and immediately leave again.