I think it's always important to look at yourself first and foremost. What part of this poor relationship do you own? What does your wife need from you which you are not providing? Are those things reasonable? Is this something you need to improve?
If you are a big part of the problem, then just moving on to another relationship will just kick the issue down the road. Sure there might be women for whom you are a perfect match and your issues don't matter, but really consider how much of your behaviors and attitudes are part of the problem.
I'm completely speculating here, but you mention bike clubs, olympic trials, and national parks. Is your wife the sporting type. Are any of these things of interest to her? It's not important, IMO, to her perfectly aligned interests, but if none of these things interest your wife, then maybe the trials and national parks is too much. Maybe you spend too much time on your bike. Maybe you are not doing enough of what she wants to do.
Of course, your wife could just be difficult and not change on your part will help. You are oil and she is water. Once you are 100% certain of this, the divorce is the best solution.
Even if you are part of the problem does not mean you are a bad guy, but a lot of us get complacent and fall back into selfish ways - thinking of ourselves and our needs. Then the wedge happens, and once it happens it gets harder and harder to repair the wider it gets.
I, too, was in a happy marriage for 12 years until we slowly started having issues. Just last year, after, 16 years, I was seriously thinking of pulling the plug. Then I did exactly what I recommend you do. I looked at myself and identified how I was not being a good husband. I let my wife know what I was going to work on without asking anything of her. It has made all the difference in the world, and, no, I was not a raging jerkaholic. I had just slowly stopped being less loving and less interested in her desires.
So I stopped complaining (so much). I stopped blaming her for things (even when it was her fault). I tried to never say anything negative about her (while still trying to not let her take advantage of me). I praised her for everything good she did. If she got angry at me, I'd gently tell her to be nice.
It took about 2 months for things to get better, but now less than a year later, our marriage is better than ever.
I'll agree, though, this is not always possible.