Actually, they never really did....

One common vein in this anthology is the leit motif of disillusionment, which, etymologically speaking, means "the state or condition of not not-seeing." A certain ideal (blindness) is lost as the price to pay for confronting situations as they really are instead. Focusing on how relationships are rather than wasting time on speculating about how they should be is at the core of this work. In this sense, the historical "emasculation" of a whole tribal identity is the real issue here, as the Chippewa Indians reveal how they first flourished, then succumbed to a "might is right" political ethic:

In the late 1700s and early 1800s, the large areas of land in the western United States that were originally settled by Indians were known as Indian Territory. As white settlers moved westward, however, the United States government passed laws that removed the Indians from Indian Territory.

The government forced Indians to move to ....new lands. As a result, many Indians had to learn new ways to support themselves. The Chippewa, for example, existed as hunters and fishermen when they lived on their original homelands. After being forced to the Great Plains regions, they had to become farmers if they were to survive.

Between 1830 and 1840, more than 70,000 members of the “Five Civilized Tribes” had to move to reservations. In Love Medicine, the Kashpaws and Lamartines lived on one such reservation, Turtle Mountain. Many Indians fought this forced resettlement in battles known as the Indian Wars.

- from eNotes.com/ love-medicine/historical-context

The "love medicine" referred to by title is the "magic potion" and false remedy for a dwindling ethnic minority seeking to preserve its identity. The battle of the sexes simply offers a context in which to address more global issues. Check out the following references for more background concerning this "Native American" (once again, a misnomer!) work.