Occasionally the surname Brennan is written as Brenan.
It would be worthwhile to try variations of surnames, when initial research gives nil result.
There are plenty of Brennans in KILKENNY especially around Castlecomer
In my own research I have found 3 variations of one surname for my family.
Is it possible that couple were not married ?
Have you looked in Census 1911 for this couple, you may find out the number of years married.
I searched for them on the rootsireland , ancestry and findmypast.ie websites, tried all different variations of the surnames myself and those websites do phonetic searches anyway.
The couple emigrated to Gateshead, England in the 1890s with their children (about 10 kids in total) but unfortunately, the husband, Patrick died in 1909 so there are no marriage details entered in the 1911 census return for his widow, Maria, she died in 1922.
Either they were never married or the marriage was never registered with the civilian authorities and has not been transcribed online from the catholic parish records because she was born in 1847 and the first child, Dennis, in 1871 so it is impossible that they married before civil registration of Catholic marriages began in 1864.
All the children were baptised and registered in Clogh, Castlecomer and as the father was a collier, I expect they lived all their lives there until they emigrated to England.
Cloneen, as mentioned in my thread title, is a sub parish of Clogh, Castlecomer by the way in case you didn't know