I am no Clinical Psychologist, but I noticed something in this riddle.
I must ask.... Isn't the Patient a Priest? And Catholic, "Nun" the less? (pardon the pun)
First of all, how is he allowed to have a girlfriend. I have always been under the impression that Catholic Priests are not allowed to fraternize or frolic either romantically or physically with the opposite sex.
My opinion; There IS a girlfriend and the discuss of knowing he is breaking his vows of priesthood is the river and God is the whale, coming to condemn his actions and those whom promote or encourage them. The rotting and decay is his faith in himself as a worthy minister, yet not being enveloped in the rot, he is not feeling completely consumed with guilt as he as successfully refrained from committing any sexual actions.
That: or the dream is about his Mom (don't know how, but consider it a guess), as there is no girlfriend in the picture.