What is the main conflict in Snow Flower and the Secret Fan by Lisa See?

"Snow Flower and the Secret Fan" is a lovely, delicate story of two women in nineteenth-century China, who pledge themselves to be soul-mates for life at the young age of seven. Although the truth is stretched to accommodate the relationship, the laotongs are supposed to have eight "characters" that match; the girls were born in the same month and have their feet bound at the same age, but it turns out that there are differences between them they only discover as adults.