I don't believe it's for their own benefit.
I thought the article was stating the dogs were bred for temperament originally yet developed a startling capacity to emotionally interact with humans via the development of intelligence.
I can't speak for your ex-wife. :P
story on a dogs act of love
http://www.moderndogmagazine.com/art...true-story/132
A study published in the U.K.'s New Scientist reveals dogs exhibit "left gaze bias," which suggests dogs can detect human emotions by looking at the face.
To be able to detect an emotion would mean the animal must also recognize the same emotion in itself. This would include love.