Being a post whore, there is a topic that is guaranteed to get hits: Sex. A recent study showed that women's sexual appetite falls as a relationship ages, while the appetite of men remains constant.
This creates a bit of a question in my mind: For women, as the "shiny" wears off, her desire to have sex diminishes. Does this mean that this predisposes women to have an affair with a new male, who would presumably trigger increased desire, or does it mean that the man who has the same desire as he always had will be predisposed to an affair with a woman that still desires sex?
In other words, are we as humans biologically designed to preclude monogamy?