They married in Maughold Parish Church:
2 Apr 1872
Robert GARRETT, Full age, Bachelor, Mariner, Lane, S Pauls Sq., [father] William Garrett, Mariner, and
Isabella KANEEN, Full age, Spinster, Sandy Road, Ramsey, [father] John Kaneen, Labourer.

Son John Garrett bapt 14 Feb. 1873 Ramsey [IGI].

The 1881 census on FamilySearch.org has:
Household:
Name Relation Marital Status Gender Age Birthplace Occupation:
Isabella GARRETT Wife (Head) M Female 29 Isle of Man, England Fishermans Wife
John GARRETT Son U Male 8 Isle of Man, England Scholar
Isabella GARRETT Daur U Female 6 Isle of Man, England Scholar
Robert GARRETT Son U Male 3 Isle of Man, England Scholar
Source Information:
Dwelling 5 Cannells Court
Census Place Maughold, Isle of Man, Isle of Man
Family History Library Film 1342346
Public Records Office Reference RG11
Piece / Folio 5601 / 5
Page Number 9

In 1891 they are in Ramsey at Promenade (Life Boat House) with John Garrett 40 fisherman b.Lonan, wife Bella 40 b.Ramsey, John Son 18 fisherman b. Ramsey, Robert Son 14 bakers assistant b.Ramsey, Bella Daughter 16 general servant b.Ramsey, Lizzie Daughter 9 scholar b.Ramsey, Leena Daughter 7 scholar b. Ramsey, Willie Son 4 scholar b. Ramsey, and Mona Daughter 1 b.Ramsey.

Sue