Anna:
Welcome to ireland Reaching Out!
The subscription site Roots Ireland has the records for Doonane RC parish back to 1814 for baptisms and 1815 for marriages. However, I got no record for a John Brophy marriage to a Keating and I additionally expanded the search to all of Ireland. Likely the marriage occurred in a parish that does not have records to the early 1840s.
If the Brophy family emigrated, you may want to add their story to our XO Chronicles site https://www.irelandxo.com/ireland-xo/history-and-genealogy/ancestor-dat…; Possibly someone will see the story and see a connection.
Have you had your DNA tested?
Roger McDonnell