To the extent Nature is conceived, marriage should never stand against our intrinsic polygamic instincts driven by our biologically pre-programmed ultimate goal of self-reproducing. Hence, it's not surprising that both men and women are following their basic instincts in the grounds of divorce, since no single life-form on Earth has been ever evolved to establish long-term matrimonial unions. However, it's well known that Humans, as highly susceptible to culture and morality, are being pushed towards the establishment of solid relationships, which in turn have been proved to play an important role in social mobility.
Based on these assumptions, it seems clear to me that there's a conflict of interests between our biological and social goals. On one hand, there's the need for each human of serving as generators of genetic diversity for the sake of continuous biological evolution, which is still happening among the human race. It's interesting to note, though, that our needs as social beings go straight in the opposite direction: we don't want to change our sexual partners all the time (at least when it comes to kinship descending) and, therefore, we end up by slowing down the diversity generation process in human race by preferring stable matrimonial engagements under social standards.
It turns out that there is a noticeable and complex interaction between genes and memes. This has been already observed by many researchers, including those working on memetic computing field. Since it seems that social evolution is surpassing biological evolution in terms of how much they affect human development (just look at how technology and culture are rapidly changing human behavior under a much higher pace than genes have done before the last decades), it's reasonable to imagine that there will come the day when the human race will transcend from its old-fashioned biological prision (i.e., the carbon-based "survival machines" of Richard Dawkins) to perpetuate itself through cultural and technological meanings.
Again, nothing new here, yet another appealing topic which should be more often discussed by academics.