We've spent countless hours and literally tens of thousands of dollars on C's. The bottom line is that W won't talk about sex. She has stopped seeing two different C's (one male and one female) when they told her that she had to address the sex issues. Her explanation to me was the same in both cases, "There's nothing more (s)he can do for me."
I'll admit that we haven't talked much about it in years, but I haven't ever seen anything change as a result of talking. The transition from no IC to twice a year occurred during counseling just after I ended an EA. I think she was afraid that I would have a PA if I got no sex at home. I can’t explain the sudden and so far enduring change from twice a year to once a week. I even had a thread last summer wherein I tried to come up with a way to question her about what changed or to come up with an explanation on my own. The general consensus and the actual result was that I quit trying to explain it and just enjoy it.
Hopefully, little changes like making a suggestion the next time she professes to be a bad lover will gradually change things some more. Time will tell.