This article uses that line as well.
"In short, we're part of a small club of primate species that are wired for the ability to fall in love and settle in with one significant other, whether or not we choose to avail ourselves of this option. This doesn't mean we're programmed to be "sexually monogamous." No species is. But we are "socially monogamous," that is, able to pair up. The fact that we sometimes experience lust in the absence of attachment doesn't make us bonobos, or mean we'd be happier with a more casual approach to mating."