A transcript of the marriage for Henry and Margaret is on the IrishGenealogy website, confirming the date you have, in addition the marriage record noted the witnesses as a William Carty and Mary Reilly - both possibly related ? An image of the parish marriage register is available on the Nation Library of Ireland website - see this page in the Rathfarnham Marriage records. Unfortunately there's no residence of other clues recorded.
I see two possible children to the couple, both baptised in Rathfarnham parish - Thomas in 1844 and William in 1847 both recorded without a mother's maiden surname... I can see that I've researched this family before, did you have a previous topic ?