Songstress Taylor Swift performed at the iHeartRadio Music Festival over the weekend, which means that she wasn’t in Massachusetts to attend (or crash) the wedding of Michael Kennedy Jr. , who married Mary Campbell on Nantucket on Saturday. Swift and boyfriend Conor Kennedy were accused of showing up unannounced to the Boston wedding of Kyle Kennedy, Michael Kennedy’s sister, last month. According to the New York Daily News, Conor Kennedy, who’s still a student at Deerfield Academy, also skipped the weekend festivities. The Daily News says that the guest list did include Kathie Lee Gifford (the groom’s step-grandmother), and Rory and Ethel Kennedy, who are set to screen Rory’s documentary “Ethel” at the John F. Kennedy Presidential Library & Museum on Monday night. Swift was first seen hanging with the Kennedys when she attended at screening of “Ethel” at the Sundance Film Festival in January.