On June 4, they were married at the Greek Orthodox Cathedral of the Holy Trinity on the East Side, before a church packed with family members and political powerhouses (Hillary Rodham Clinton and Mr. Kelly sat on the bride’s side, and former Secretary of State Henry Kissinger and Mr. Giuliani on the bridegroom’s) and a tittering clutch of Ms. Catsimatidis’s high school friends. “Can we talk about the fact that this is actually happening?” one of the young women, round-eyed, said to a friend.