There were 2 main RC churches in Belfast in the 1830s – St Patrick’s and St Mary’s. St Pat’s records start in 1798. St Mary’s – the first Catholic church in Belfast - opened in 1784 but it has no records before 1867. Presumably they were lost. So if you can’t find the marriage in St Pat’s records then one possibility is that they married in St Mary’s (tradition was to marry in the bride’s church). If they did marry there then, sadly, there will be no record to find.
The other thing to consider is the possibility that they married outside Belfast. Throughout the 1800s folk were pouring into the city from the surrounding counties, drawn by the new employment opportunities created by the mills (there were over 50) and other industrial activity eg ship building and related industries like iron foundries etc. So they might have married elsewhere. (When St Mary’s opened in 1782 there were just 365 Catholics in Belfast out of a population of about 20,000 people. By 1911 the population had risen to 385,000, of which 24% were RC. So that gives an idea of how many people moved into the city from country areas in the 1800s).
Most, though not all, surviving RC parish records for Ireland are on Ancestry. I searched them for a marriage around 1830 but did not find one. I suspect therefore that there is no record of the marriage to be found.
