Thanks for sharing that. Here's what I know about the Himba:

"It is not uncommon for a married Himba man to take one of his several wives with him to the cattle stations or to have a girlfriend there (unmarried men spend time at the cattle stations as well). And many of the Himba wives who stay behind in the main camp take lovers while their husbands are away.

While they are not unusual in that they cheat, the Himba are remarkable in their relative openness about their extra-pair involvements. Married people discuss their “affairs” more freely among themselves than we do, certainly, and also speak about them with anthropologists like Scelza, probably because there is little reason not to: the Himba are one of the rare cultures where there is not the kind of taboo against adultery that we have and might expect to be “universal.” Spouses expect a degree of consideration from each other, to be sure, and there is a code that governs how lovers are to behave—“I don’t like it when her boyfriend is here in the morning when I come back from being away” is the gist of what one Himba man told Scelza. As Scelza explained to me, “There’s a framework, and there has to be respect.” But affairs are an open secret, or perhaps more accurately a non-secret."

Martin, Wednesday. Untrue (p. 121). Little, Brown and Company. Kindle Edition.