Hi Julie
I can't actually see a record of the marriage (on the resource I'm looking at) ?
That doesn't mean of course that there wasn't one, but 1842 is before the date of official registrations for NZ, so it may be that a church record (in Nelson), is all that's available. (Maybe make an enquiry re: church records, at one of the links I gave previously.)

~ Lu
PS : I'm sure there's a webpage somewhere I've seen, with these early Nelson BMD's. Will try and find.