Rather than looking to phsyiological causes of his unwillingness to perform sexually, it seems more likely he is tortured by guilt, maybe unacknowledged guilt, or other strong emotions. Maybe regret, sorrow, confusion. As they say, the most important sex organ is the brain. If I were in his shoes I'm sure I would feel odd.
but of course I still think Patti is the best judge here. (Sorry, Patti, I am not sure of the spelling of your name)
M 43 S14 S13 D11 D7 Divorce final: Jan 2009 Making it up as I go....