You could search the church records. If they were Catholic, Cleenish parish
records are on LDS film 979705, items 1-4. Baptisms go back to 1835, but
marriages only to 1866. Part of Cleenish civil parish is also in Enniskillen RC
parish. Those records have not been filmed by the LDS but are in the NLI and
PRONI. If they were not Catholic, you should be able to find their marriage in the
civil marriage index.