The footnotes found in the scriptures really do provide wonderful contextual hints. For instance, consider footnote
a from verse 19 of chapter 7 in the book of 1st Nephi:
19 And it came to pass that they were angry with me again, and sought to lay hands upon me; but behold, one of the adaughters of Ishmael, yea, and also her mother, and one of the sons of Ishmael, did plead with my brethren, insomuch that they did soften their hearts; and they did cease striving to take away my life.
19 a daughters 1 Ne. 16:7; 18:19 (19–20).
This verse tells of the struggle Nephi had with his brothers and some of the sons of Ishmael on the way back to Lehi and Sariah in the wilderness. He received meaningful aid from one of the daughers of Ishmael, who is strongly implied (in the verses appearing in the corresponding footnote) as becoming Nephi's wife:
7 And it came to pass that I, Nephi, took one of the daughters of Ishmael to wife; and also, my brethren took of the daughters of Ishmael to wife; and also Zoram took the eldest daughter of Ishmael to wife.
19 And Jacob and Joseph also, being young, having need of much nourishment, were grieved because of the afflictions of their mother; and also my wife with her tears and prayers, and also my children, did not soften the hearts of my brethren that they would loose me.
20 And there was nothing save it were the power of God, which threatened them with destruction, could soften their hearts; wherefore, when they saw that they were about to be swallowed up in the depths of the sea they repented of the thing which they had done, insomuch that they loosed me.
And that's why we always check the footnotes.
The Church of Jesus Christ of Latter-day Saints has recently released a series of videos on youtube depicting events from 1 Nephi through 2 Nephi chapter 5. They are wonderfully done--go watch all of them! The producers of these videos must have come to these same conclusions about Nephi's wife: