There are sources for marriages that the Provincial Archive of New Brunswick doesn't have or isn't showing
Heads up for my peeps trying to chase vital records into the 19th century in New Brunswick!
It looks like FamilySearch.org has images of at least one register of NB marriages, 1857–1875, that's not coming up on the Provincial Archive of New Brunswick, despite the fact FamilySearch.org cites the NB Archive as their source.
I was surprised and pleased to stumble over an image of the marriage record of my husband's G-1 on FamilySearch, but when I went to check the Provincial Archive search engine for their copy of it, not only didn't that record come up, I discovered no marriage records before 1888 are being returned by their search engine. The intro page of the search engine says they include the corpus FamilySearch cites (index 141B7, "Index to New Brunswick Marriages, 1847-1975"), but their PDF guide says their marriage records don't go back before 1888.
I just filed a bug report with the NB Archive about this. Not sure if they're supposed to be returning pre-1888 records and just aren't, or whether they're not including the records back to 1847 and should update the description of their search engine.
Meanwhile, trying to sort this out, I discovered that there was published in 1985 a book in two volumes titled Marriage Register, Westmorland County, N.B. "Compiled by Ken Kanner and V. Bing Geldart." Volume 1 is 1790-1856 and Volume 2 is 1857-1888. ISBN: 0969164211. There's copies in a very few libraries; search for it on WorldCat.org to find the one closest to you. I have no idea what the insides look like. Could be photo reproductions, could be a transcription (which would be less authoritative.)
So, I guess if you're looking for pre-1888 marriage records from NB, be sure to check FamilySearch.org if the Provincial Archive isn't cutting it. As a last resort, if you think the marriage was in Westmorland County, you might have access to a hard copy book near you or be able to access it through inter-library loan or requesting a librarian look up your record for you.
Finally, the Vancouver Public Library – yes, the one in BC, no, I have no idea why – has a tantalizing page on their holdings of 19th century New Brunswick church registers of vital records.