I have never been in extended chronic pain, but the extended depression over my marriage has caused me to lose interest in my wife sexually. Nevertheless, I still need it alot. And when she asks, I will still give her sex and it is a huge relief to me. I agree, I have never met a man who doesn't want a lot sex.
So maybe chronic pain is different and causes loss of sex drive. I'm not a doctor by any means.
But if he is saying that he thinks you don't want him, it may be a combination of pain, depression, and feeling unwanted. It is also his responsibility, though, if he is feeling unwanted, to boost his own self-esteem and make himself feel more desirable.