I have asked my doctor a number of times if I really have fibromyalgia and wonder if it could be something else like CFS.
I haven't been diagnosed with CFS, altho a specific form of fatigue is my main and debilitating symptom, but I don't depend on docs as I don't tolerate meds, and am always looking over that non-existing fence to what helps CFS, which is easy to do if I follow Cort Johnson's healthrising.
but things always devolve back to status quo
Yeah, that's a tough one, some people more change resistant than others, but everyone a bit, being human.
I have various techniques to help remind, like sarcasm ("strange my body doesn't obey your mentality, maybe we should buy a more obedient one"), putting things in a nutshell ("pushing thru will make it worse, slowing down will make it better: do you want it to get worse or better?") or writing down for myself (and praps her) and repeating the core phrases that "worked best" to understand.
Relationship spin-offs similar to this was something my psychologist helped me with.
Things that helped my (admittedly caring, German

) wife:
pre-fibro seeing all the effects of all my difficult foods on my gut (something unknown to her)
fibro-buildup: seeing me cry from wind and cold, altho I never cry,
seeing my stiffness every time I get up from sitting etc., that was what made her send me to rheumatology.
So seeing is believing (how silly, actually), and if someone doesn't see, which in the case of invisible conditions is often the case, then we have to show our emotions openly, and describe the symptoms.
Also seeing that I'm doing all I can and researching like mad helps her see I'm not resting on my oars for the fun of it.
Another one: realizing that the backlashes from overdoing it are seldom worth it.
That can only be made clear if we learn what overdoing it / pushing thru feels like, during and after,
learning to identify for ourselves and point them out to the other person, so they can "follow" what's happening.
One of the problems is my rest of social anxiety concurring with social situations now being a major stressor, that's one point where she does push me over my limits and usually doesn't see it, believing that my extraverted part needs nourishing too, which has greatly decreased...
That's when i do have to sometimes describe the pain beforehand, until she sees it in my white face and lips.