I searched the Irish Family History Foundation's database. Portions of Co. Roscommon's surviving rcds are in it. Entire parishes' rcds remain undigitized. Rcds B4 1840 are sparse. For questions abt these parishes contact firstname.lastname@example.org. Boyle rcds for 1793-1900 are in the database.
I couldn't find B rcds for Mary Ann McPartland (+variants) in a range around 1862.
I couldn't find B rcds for Owen McPartland (+variants) in Roscommon, ever. The same is true for Ann Frazier. There also are no marriage rcds for the two.