Maybe you're just **** at it.
Become a polygamist and marry a second wife that is a wildcat in the sack. If Mrs. Frigid don't like it tell her she needs to satisfy you then or else you will find someone who will. Do not cheat, make sure to marry the second one so its not adultery first.
what did you really do about the problem ? I have a wife who has issues too
Tell her to shape up, or ship out.
Find HER point...
I would suggest an open relationship. We went through a dry spell where she was disinterested. She was having some health problems at the time. Some friends of ours wanted us to join them in swapping. She wouldn't do that but wanted me to have sex with them......so I did and it opened us up to lots of new things that got her excited about sex again.