I searched the Irish Family History Foundation's online database at ROOTSIRELAND.IE. It has abt 20M B/M/D records for most Irish counties. Records before 1863 are increasingly sparse: almost non-existant before 1800. Protestant records are scarce at any date. The surnames for Rose's parents suggest they were Protestant; hence, likely for Northern Ireland.
For a ?? McGuire and ?? McGukin marriage in 1867 +/- 5 yrs, somewhere in Ireland, with the parents' names unknown, I found 1 record in 1862, Co. Leitrim. However, the names are Catherine McGuire and Andrew McGukin. This is way off the mark to be for your ancestors.
For Sar(..) McGukin B 1850 +/- 5 yrs, somewhere in Ireland with the parents' names unknown, I found 6 records.
For Ter(..) McGuire B 1848 ditto, I found 22 records.