I've been thinking about you a lot today, Crimson. My personal mantra has been, "Become the spouse only a fool would walk away from." It sounds like, in many ways, you (and even your friends and family) feel like you've become that kind of spouse. So, if she still walks away... what does that say about her? (It seems like it says a lot more about HER than it says about YOU.)
As wonderful as she is, she is by no means the only one out there. You may never be able to understand her actions... they just may be totally irrational.