I did some searches on the subscription site Roots Ireland and did not find any James Ryan/Anne O'Brien marriages prior to 1844.
I also looked for baptismal records using the parental names provided but could not find a John and Mary born in the same area to parents James Ryan and Anne O'Brien.
Likely they came from Co. Tipperary or Co. Limerick.
You may want to consider DNA testing and possibly you will get matches on your Ryan/O'Brien lines.
Roger McDonnell