I just don't have the nerve even though I've felt comfortable talking with him about other things. Every time I decide to talk about it, the words won't come out. I'm not wasting my time there, but I'm also not solving the problems that I need to. It sounds like other than talking about the sex problems, you feel comfortable with your therapist. I would advise trying some other ways to get the discussion going with him first.
Sexual problems are usually difficult for anyone to talk about even under the best circumstances.
For many women, discussions about sexual matters are more difficult to talk about with a male therapist than a female therapist. However, many women see no difference, and some even prefer to talk to a male. You may want to say it's difficult to talk about with a man. Your therapist wants you to be able to discuss your difficulties, so he will probably be very supportive and will do whatever he can to make you as comfortable as possible while encouraging you to go ahead. Write him a note telling him your sexual issues.