Hi
No relation! But no wonder you couldn't find the marriage of Patrick Allen to Mary as she's variously known as PENTLAND, PEUTLAND, PINKLETON, PINGLETON, and PETLAND, according to the fabulous records on http://churchrecords.irishgenealogy.ie/churchrecords. Here is their marriage details:

Area - DUBLIN (RC) , Parish/Church/Congregation - ST. ANDREW
Marriage of PATRICK ALLEN of 178 TOWNSEND STREET and MARY PEUTLAND of 7 CASTLE MARKET on 20 October 1872
Husband Wife
Name PATRICK ALLEN MARY PEUTLAND
Address 178 TOWNSEND STREET 7 CASTLE MARKET
Occupation N/R N/R
Father HENRY ALLEN JOHN PEUTLAND
Mother N/R N/R
Further details in the record
Witness 1 MICHAEL O'CALLAGHAN
Witness 2 MARY ANNE HAMILTON
About the record
Book Number Page Entry Number Record_Identifier
N/R N/R N/R DU-RC-MA-43957
The church register page containing this record has not yet been imaged.

There are loads of other records for the baptisms & marriages of their children, some having the address Tracy's/Treacys Cottages, which is how I know your Mary's surname.

Enjoy perusing the site - I'm sure you'll find lots of interesting stuff!

Cheers,
Colette