in 2015, the Pitcairn Island, population ~50 people, passed the law for legal gay and civil law marriage. there were no gay couples or people on the island at the time. the law was unanimously approved.
"Warren said she knew of just one islander who had identified as gay, and that was a long time ago. And she said any gay couples wanting to marry might have difficulty, as the island’s only preacher was a Seventh-Day Adventist, a religion which opposes gay marriage. She said the island administrator might be able to officiate." source