Pauline,
The Maughold parish register has this for the marriage:
10 Jun 1854
Daniel LOWEY, Full age, Bachelor, Smith, Ballachrink, [father] Patrick Lowey, Smith, and
Catherine KERMEEN, Full age, Spinster, Cardle Voar, [father] John Kermeen, Weaver.

The closest Cath, daur of John, to the age you gave is Cath daur of John Kermeen & Ann Kermeen bapt Maughold Parish Church 29 Nov 1827. [They married Maughold 13 Oct 1827.]

However there is a Cathrine in the Maughold 1841 census closer to the age you gave, and living at Cardlevoar [adult ages rounded]:
3 3 10 Cardlevoar
John KERMEEN 35 Isle of Man
Isabella KERMEEN 35 Isle of Man
John KERMEEN Junr 15 Isle of Man
Robert KERMEEN 10 Isle of Man
Cathrine KERMEEN 8 Isle of Man
James KERMEEN 1 Isle of Man

John son of John Kermeen & Is Cleator bapt Maughold 12 May 1825.
Robert son of John Kermeen & Isab Cleator bapt Maughold 29 Jul 1827.
James son of John Kermeen & Isab Cleator bapt Maughold 30 Sep 1839.

I think the parish clerk may have made a mistake and put Catharine's bapt as father William Kermeen:
Catharine daur of William Kermeen & Isab Cleator bapt Maughold 9 Dec 1832.
I can't see any other bapts for the children of this couple, and no marriage found. That seems to be the answer to the missing baptism.

John Kermeen & Isabella Cleator married Maughold 18 Feb 1825.
Isabel daur of Robert Cleater & Mary Kissage bapt Maughold 3 Apr 1803.

In the 1851 Maughold census, at Cardle Moar, all b.Maughold:
John Kermeen Hd mar 47 Ag lab
Isabella Kermeen wife 49
Robert Kermeen 23 S?ailor master
James Kermeen 12 Scholar

In the 1851 Maughold census Catherine Kermeen aged 19 was a servant in the household of Daniel and Elizabeth Joughin.

Isabella KERMEEN, 58, of Cardle Voar, was buried Maughold 24 Oct 1857.

At Cardle Maughold in the 1861 census:
3 97 Cardle
John KERMEEN Head MAR 54 Weaver Maughold
Mary KERMEEN Wife MAR 30 Lezayre
Mary Ann KERMEEN Daughter 2

[Maughold parish register]:
Mary Ann daur of John Kermeen & Mary Ann Caine bapt Dhoon Church 23 Oct 1859

John Kermeen & Mary Cain married 30 Nov.1858 Ramsey.
If you look up the Ramsey marriage record in the MM, or in the LDS film no.0106182 available through FHCs worldwide you will see further details including (probably) that John was a widower.

There are about 5 possible John Kirmeens bapt in Maughold around the ages he has given. You need to look at Kirmeen/Kermeen wills to try to find refs to him and his wife and children.

See Mau [Maughold] at www.iomfhs.im/lawsons/wills/ke1-will.html
for dates and LDS film numbers.

There may be a M.I. for John Kermeen which includes Isabella Kermeen / Cleater.

Sue