Well, since anthropologists since the 19th century have been as obsessed as missionaries with the topic of sex and kinship (see M. Head's works or Malinowski's (somewhat mistitled) "The Sexual Life of Savages", etc.) I think I can offer some insights here.
First, I will mention that, from a Darwinian perspective, it is worth noting that women are "k-selected" because they invest so much time per child while men are "r-selected" because, from a genetic point of view, their role is done in minutes. However, that doesn't really tell us that much because culture has a habit of over-riding.
So, just how common is our (older?) pattern of life-time monogamy? Not very and as often as not in very predictable circumstances (from what is now a Marxist structuralist perspective). I would say that many monogamous cultures also recognise that people and circumstances change so that staying with someone when you our grow, each other, etc., is just dumb. So commonly, in these contexts, there are few problems with "divorce" and remarriage. In fact, a woman who has demonstrated the ability to have children would be desired (i.e., more than a virgin), not stigmatised in any way.
So, where does "our" version of monogamy tend to be most often found? First, in patrilineal societies where property, etc., passes down through the male side. Obviously, in matrilinal societies, when property is passed down through the female side (i.e., inherited from mother's brother) there is no problem because who the mother is is generally never in question while who the father is is unimportant (in fact, it is not uncommon for it to be believed that the father plays no real role in reproduction).
So, monogamy tends to be highly correlated with property being passed down through the male side because only then is it really important who the father is. But this does not eliminate polygamy. In fact, the early Christians were frequently polygamous (i.e., note that the apostle Paul said that only pastors and deacons of the church should be monogamous - have only one wife). The choice between monogamy and polygamy is very much linked to the economic system. Cross-cultural rule of thumb: where economic units (i.e., families) are more self-contained, polygamy is favoured because it allows for a concentration of wealth and resources in extended families (depending on the nature of those resources, of course). Where economic units contribute to a larger entity (i.e., the "state" by way of taxes or tribute, etc.), then monogamy is favoured, which also cuts down on wasteful competition or raiding for wives, etc.