I can help you understand what may be going on with your boyfriend, but I think you need to be asking yourself why you want to be with a man who is disinterested in sex. You also need to ask yourself if you are willing to live without sex for the rest of your life, because there is a good chance that this is what is going to happen, since he doesn't seem to be chomping at the bit to get help for his problem.
My point is, you are focusing on what you can do to fix or change him, when he isn't asking for help for his sexual dysfunction. Instead of focusing on him, focus on you.
Understand why you want a man who doesn't want you. Understand how this sexual deprivation recreates your childhood wounds (see my advice archives under repetition compulsion and unfinished business). I have the sense that somebody didn't meet your needs or love you enough when you were young, which would explain why you would choose a man who can't give you good loving in the sexual arena.
If you've been reading my columns for a while, you know that people tend to recreate what is familiar. So, if you were deprived of love as a child, your mind would choose a lover who deprives you. The unconscious fantasy being that if you can get your depriving lover to give you what you want, then you will feel as though you are receiving what you lacked in childhood, thereby healing the old wound.
As you can see from your question to me, this is exactly what you are engaged in, trying to fix your boyfriend and make him fork over the goodies. Before you embark on trying to help him to heal, understand yourself and your attraction to him.
If you still want to take on the task of helping him, then you need to engage him in the process. He needs to open up and tell you everything. He needs to commit to work on resolving the issue with your help and with the help of a professional.
If he refuses to engage in the process, then what you see is what you get, in which case you will need to make a hard choice. Accept him as he is, and accept that he will never change. If you can't accept this, then you will need to move on. If he agrees to work on his issue, then he needs to first understand that his therapy has been ineffective in resolving his issue.
I don't know what type of sexual deviance he was arrested for, so let's assume he molested a child. It sounds like the treatment that he received consisted of teaching him to suppress (or bury) his sexual urges toward children.
The problem with the suppression approach is that it leads to a complete, across the board numbing of his sexual desires. Being sexually dead may limit his risk of future sexual deviance, but it leaves him unable to have a 'normal' sex life.
He needs to find a therapist who can help him learn how to regain his sexual urges (including the deviant ones). Then, he must learn to not act inappropriately.
The point is, most people who aren't completely repressed admit to having sexual urges toward children, family members, and members of the same sex. But, not everyone acts on these urges. All humans must learn to accept all their impulses, sexual and aggressive, and control their behavior.
A good psychoanalyst should be able to help him separate him impulses from actions. Then, when he is sure that he can control his behavior, he will feel safe to reclaim his sexuality, which will mean that you will get lucky.
Realize that even if he agrees to get help, that this process is a slow one. Make sure that you are willing to wait and go without in the meantime.