John Dempsey and Catherine Crowley married February 16 1840 at the Courceys Country RC parish.also know as Ballinspittal. I also located three baptismal reocrds for children. The dates are baptismal dates. Are you aware of other children?
Mary February 2 1841
Patrick September 19 1843
Dan March 25 1847
The 1852 Griffiths Valuation head of house hold listing for Ringrone civil parish showed tow John Dempsey records. One in Ballymackean townland and the other Oldcourt townland. Likely one was your ancestor. https://www.failteromhat.com/griffiths/cork/ringrone.htm