Ref. St. Patrick's Parish (RC)Waterford Marriage Registers; The National Library of Ireland seem not to have a Marriage Register for St. Patrick's Church 1800 to 1827. Anyone know if said register actually exists anymore seeing as NLI haven't got it up online?
The RootsIreland site indicates that they have the records you want.
Now there are two possibilities.
1) The records exist - NLI simply did not film them. I personally know this has happened in several cases. Or
2). The records actually don't exist, and RootsIreland has neglected to indicate a gap in their coverage. I know that has also happened in other cases!
I have no idea which is the case here.