I couldn't find this marriage at all on Emerald Ancestors so I'm a little puzzled by this thread. Also all marriages I have looked up on the site give an exact date and place of marriage - unless you don't have a subscription (but in that case it only gives county and year - not parish and religion - and doesn't give both surnames).
For registered events (such as post 1845 non-catholic marriages) GRONI is the place to order certificates from, not PRONI. For marriages, if you have the exact date and place (from Emerald Ancestors), it's much cheaper to order the certificate from the district registrar (Emerald also tells you which one, but Lisburn covers Derriaghy). Also note that while the family may have attended one church (usually the husband's family church), they are often married in the bride's family church which maybe different - even if they are both Church of Ireland.
I did find the following in the civil registration indexes:
Jane Alderdice, Marriage, Lisburn District, 1850 Vol 7 p73
which would allow you to order her marriage certificate from
GRONI, but no Partridge has the same reference so presumable this Jane married someone different or John used a different spelling of his surname.
You can search for yourself free at:-
http://pilot.familysearch.org/recordsearch/start.html#p=collectionDetails;t=searchable;c=1408347Another option would be to search the Belfast Newsletter for a marriage notice - I think there is a subscription site which has indexed this 1740-1900. If the family was prominent locally, a newspaper announcement is a reasonable possibility.
Good luck in your search.