I searched the IFHF's online database at ROOTSIRELAND.IE. It contains abt 19 mllion B/M/D records. MOST counties, including Antrim, have had their records transcribed into the database.
For Edith Trimble B 1882 (exact) with a father forenamed Robert, and mother forenamed Marg(aret), in Co. Antrim, I found 1 B record. This is highly likely to be for this ancestor. A view of the detailed record MAY reveal more detailed information.
For a R(obert) Trimble and Marg(aret) ????? marriage in 1880 +/- 2 yrs somewhere in Ireland, I found 0 records. They may have married elsewhere, the records may not have been transcribed yet, or the records didn't survive.
For R(obert) Trimble B 1859 +/-5 yrs, somewhere in Ireland, wth the parent's names unknown, I found 1 rcd in 1864, Co. Armagh. NOTE - this date doesn't coincide with your information; therefore, it may not be for this ancestor.
For Marg(aret) Gowan B 1862 +/- 2 yrs, somewhere in Ireland, I found 21 records. Again, you have a problem in deciding which, if any, is the correct one.
The surname Trimble hints at being protestant while the Gowan surname suggests RC. If so, this may have been a mixed marriage. Such an event wasn't socially acceptable then (and now).