I once spoke to a psychiatrist about this very subject, when a girlfriend decided that an armed robber was a more suitable partner and role model to her son. Also my sister who is upmarket and well educated has a fancy for the dog ends of society.
His reasoning is that there is nothing to live up to, no standards to keep and nothing to aspire to, which they may find has been tiring. So with these "dog ends" they can just slob about and are under no pressure to be better than they are inclined to be at that moment. In the case of the armed criminal, it seems that some women crave excitement. They would never do anything like that themselve, but live out their "Bonnie and Clyde" fantasies through their partner. I believe that these two split up after creating another child in about twelve months. Not heard of her since.
