I'm in this situation, too, but I think I caused it. At the start of our relationship, we would have sex. My DH always initiated it. I discovered fairly quickly that his idea of sex was penetration with an orgasm for the man. I had a fairly conservative background, but I'd always had mutually satisfying sex, so it was a complete turn off to learn that sex with him would make him happy and leave me frustrated.
With all the optimism of youth and having previously been with emotionally mature partners that would talk about feelings and sex and whatnot, I tried to talk to him about it. He came up with a number of responses, from, 'but I thought women didn't get anything out of sex' to 'but I thought all women orgasmed via penetrative sex'. I think he was trying to find the thing that would bring the conversation to a close. Once he realised he would have to make an effort in bed, the times we actually had sex per month went into single figures, then hit zero.
At the weekend, the fact that we had not had sex for 18 months suddenly really got to me, and, rather unwisely, after nearly a bottle of wine I raised it with him. He was fairly jovial about it, the discussion was fairly jovial. The next morning he kissed me, put a condom on and, well, 'made good progress', as my driving instructor would have said. It was good for him. I somehow felt I'd been taught a lesson. I think it's put me off sex for a good while.
God, I could cry.