I'm trying to marry Camilla, yet she keeps on walking off & disappearing half way through the ceremony.
Now according to the Wikia there is an XBox bug that causes her to do this if you don't already own a house - however I'm on a PC & I own Breezehome in Whiterun!!

I'm on the patched version of the game - anybody else having similar problems??

As I understand it, this always happens during marriage, (from what I read) and I have tested marrying a handful of different NPCs and they always always always start heading for the door when the priest is rounding up the ceremony. (I play on PC, and own a house, since you mentioned an Xbox house bug )
Cancel the priests conversation and interract with your spouse to get the newly wed dialogue, immersion breaking, yes, but oh well.

EDIT: I encountered this before the patch.