I like the explanation of why they did not recognize each other in Child #52, King's Daughter Lady Jean:

"The very first time I came from sea
Jane you were unborn
And I wish my gallant ship had sunk
And I'd been left forlorn
And I'd been left forlorn"

"The very next time I came from sea
You were on your nurse's knee
And the very next time I came from sea
You were in this wood with me
You were in this wood with me"