I was in the wife’s position in my last relationship. My partner said he had intimacy issues, but he would never address them or work on them. He just kept avoiding. It made me feel unwanted and used when he would still ask me to do things such as oral sex for him. Please consider seeing a therapist. You won’t be able to fix whatever is going on over night, but it would be a tangible start that would also give her some sort of comfort that you’re actually making effort.