 Nancy is the one who tells Jack.Unbeknownst to Avery, Liz and Jack are accidentally married to each other in the Caribbean.The officiant whom Jack and Avery had hired for their wedding did not speak English and in due course honestly mistook Liz for the bride because she answered his request for a vow of commitment "oui" while wearing a white tennis dress and a white mosquito net (her clothes having been lost in an luggage mishap) and standing next to Jack at the altar (as best man after Bob Ballard failed to make it).