Hello Georgia,
There are no records of an Eleanor Kaighin marrying John Crain(e) in the Isle of Man that I've come across - so there are a couple of possibilities:
1. They married abroad. Have you checked UK or NYC marriage records?
2. She was a widow when she married John.
There is also one other possibility. My family of Kaighins had two brothers who came over many years apart. One was John Kaighin and the other Charles (my GG Grandfather). John came over in 1824 after marrying and fathering 13 children with his wife Eleanor Cannell. Most of those children came over with him, including his daughter Eleanor.
This Eleanor was christened 28 Oct 1801 in K. Michael (the family lived at Kerrowglass farm on the border with K. German). The problem here is I have an unsourced reference that she married a "Mr. Kelley" in NYC. The reference is the Florence Lyon Genealogy Chart, which is deposited in the Manx Museum and which several of my branch of Kaighins are in possession of. I know nothing further of Eleanor, except that she was alive in 1841 when she was mentioned in a letter written by my GGG Grandfather at that time.
You can read more about this family here, Eleanor is in family 9400:
www.kaighin.com/FamilyHistory/Requests/John_Kaighin_Elizabeth_Nicholl.htm
Also, if you can determine that this is your line, I have been able to successfully trace this family back further than John Kaighin and Bessy Nichol.
Kind Regards,
Greg Kaighin
www.kaighin.com
Honolulu