It's probably actually because of you reloading a save - the save file doesn't include marriage status. So any time you load, you have to wait another 20 seconds for marriage to happen.
But it happens mid-game, after using the active ability, sometimes two or more times, of course each time after using the ability. Haven't reloaded the game in between. Almost like the construction destroys the ring when starting and restores it when finished.
