Nice post, nomad. I've always believed the separation was an effect of the law of diminishing marginal utility -- where the longer one uses something, the less satisfaction one gets from it. In marriage, this translates to couples who initially told themselves they'd die for each other, eventually getting bored with themselves. The guy who during the early stages of the relationship averred that he'd fight superman to save his woman's life now doesn't care as much. I just used to think that was the reason for the divorce statistics, and that because we're humans, it was just meant to happen because we get bored easily, even in marriage. The ones who stayed together for so long I termed anomalies in the whole general equation.
But frankly, your post shed light on some key areas I didn't think of. Thank you for that.