Silk is already getting this "wife" thing down, pat. And a good thing too, because Cain is apparently a natural-born ladykiller. His adventurer tutors are gonna be heartbroken.
As for the date thing...I mean, don't you just explain it as it happened? If they have any problem with it, best address what the rules are earlier rather than later. If not...I mean...you are getting married. This seems like a good start to a relationship.