Starting June 4th, official support for wedding ceremonies in Vana'diel will begin! For details, see the Wedding Ceremonies pages of the FINAL FANTASY XI Compendium via the PlayOnline Viewer. Be sure to also read  "Weddings in Vana'diel":

One result of the recent summit in Jeuno was the approval of marriages between adventurers. We asked those organizing the ceremonies for their impressions of the wedding halls and facilities in San d'Oria, Bastok, and Windurst. 1. San d'Oria San d'Oria's dignified weddings are emblematic of the strong traditions that pervade the city. A San d'Orian wedding is a fitting way for a couple to swear their eternal love and receive the blessings of the Goddess. 2. Bastok The Republic of Bastok offers wedding ceremonies with an atmosphere of freedom and a guarantee of satisfaction. The Department of Industry promises that you will cherish this day forever. 3. Windurst First brought together under the bejeweled night sky, you shine like two stars snuggling up to one another. The Sibyl Celebrants proffer the blessings of the Star Sibyl in honor of this special occasion.