passion... even if the passion is mixed with fear, setbacks, confusion... but whatever you do, let your no be a no and your yes be a yes. No bells and whistles, just honesty. No one is expecting perfection, but they do expect humility.
We would write our own ceremony, but I think I would like a reading from his mother taken from the bible. Either the Corinthians passage on love (because it is sweet) or something from the Song of Solomon. Although it is kinda dirty.