Love Me, Love My Dog
The truth of this statement is borne out by an anecdote in this article
She confronted him about this at dinner one night, and he confessed, in some anguish, that he didn't love Sophie, didn't love dogs in general, never had.
They broke up the next week. More accurately, she dumped him. "What can I say?" Edie told me, somewhat defensively. "Sophie has been there for me, day in and day out, for years. I can't say the same of men. She's my girl, my baby. Sooner or later, it would have ended."
The article goes on to speculate about why humans love dogs and concludes it's because they're cunning charmers:
Or, to look at it from the opposite direction, Archer suggests, "consider the possibility that pets are, in evolutionary terms, manipulating human responses, that they are the equivalent of social parasites." Social parasites inject themselves into the social systems of other species and thrive there. Dogs are masters at that. They show a range of emotions—love, anxiety, curiosity—and thus trick us into thinking they possess the full range of human feelings.
This catches a bit of it, but more than that, I suspect humans and dogs have evolved together for reasons that annoy the neighbors of people with dogs; the fact that they bark when they hear somebody. For most of human history, knowing when others were approaching was potentially critical to remaining alive.