We knew his father was strange and unstable, now we know that he is a deviant too, and we also learned that the desertion was something he actively encouraged while he was safely 8,000 miles away.
Bowe Bergdahl left home at 17 or 18 to move in with his ballet teacher - it sounds more and more like he had a good reason to leave home and to sign up with both the Coast Guard and the Army.
To get away from his psychopathic, self-aggrandizing father.
It also explains that silent scream of despair look his wife had on her face at the rose garden. Then again, she may be just as whacked as her husband.