This sounds very frustrating! I am wondering if there is any history of sexual abuse or molestation? There could be so many reasons for the lack of sexual initiating or responsiveness I would recommend couples counseling to really be able to address the underlying negative dynamics.
I can be reached on my confidential office line (415) 381-1065 for an intial free telephone consultation which usually takes about 15 minutes.
All my Best
Ondina