Wow, there are many similarities in our situations. If I may ask, does your wife has orgasms with you or by herself? Has she ever? Perhaps I'm overly focused on this aspect of a relationship since it seems to be a major stumbling block in my marriage, though I won't claim for sure that it's the root cause of our problems.
It certainly seems to be a stumbling block in my marriage that my wife never explored herself far enough to experience orgasm for herself, and has not let me try, and doesn't want to talk about it any more. So with other issues on top of that, it becomes more difficult to frame success as "getting back to the good thing we had when we met". We now realize we never quite had it as far as a good mutual sexual relationship.
It would be one thing if we had dealt with this issue early in our marriage, but it's another kind of probem when it hasn't been resolved in 30 years. Compared to the problems I read other couples have, I often feel like they just have easy problems to fix. Like we never had the sexual thing right ever, so the sexual prospects are not encouraging, though much else about our marriage is good.
