Faith's pink ribbons are mentioned three times in the first 6 paragraphs. Why does the author make such a point of this?
The ribbons are symbols of Faith's purity and youth. They are decorations that a young, pure, faithful wife can reasonably wear, even in Puritan society, and not be considered vain. Hawthorne mentions them so many times to enforce the idea of Faith's purity. As Young Goodman Brown leaves her, he can still see her ribbons blowing in the wind, and he is reminded, once again of her purity.
Later, he recognizes Faith in the forest at the witches' coven meeting, and she has her pink ribbons again, but this time they fall out of her hair, indicating that she has lost her innocence and purity. This represents the final catastrophe to Young Goodman Brown, who has already seen his father and several other supposedly upstanding, righteous people consorting with the devil. And now, he sees his once pure and innocent wife.
Interestingly and mysteriously, though, when Young Goodman Brown returns home at the end of the story, there is Faith, and she still has the ribbons! So-- did he imagine everything? Is she still pure and innocent? That is the intrigue of the story.