I experienced a couple of bouts of Fibromyalgia as a 'lucky' addition to Psoriatic Arthritis.
To give an idea why she might seem lazy, snappy and grumpy, all I can do is tell you what it felt like for me (taking into consideration I am familiar with feeling ill and in pain with a relatively manageable condition).
When I woke up in the morning, I felt like I'd been hit by a bus, dragged along the road a bit, shovelled up and hurled into a cement mixer with half a ton of cobbles. I felt bruised and battered. My neck felt as though my head was in the process of falling off, I was dizzy, vaguely nauseous and, by the time I was waiting for the bus home for work, if I couldn't sit down out of direct sunlight, I would have to sit on the pavement or risk fainting. I fainted in public three times - walking hurt, my legs felt as though they were made of lead, but it was still easier than having to stand still for a few minutes.
When I got home, the prospect of having to get up off the settee to go to the toilet was so unappealing due to the pain and the fact I'd be out of breath by the effort, I stopped drinking any fluids at all to reduce the number of times I had to get up (and obviously got very dehydrated and more likely to faint as a result). The effort of sitting upright was exhausting.
I needed (but didn't get) help to get up the stairs, get undressed and get into bed. A shower - with a garden chair placed underneath it - was so much effort, I'd have to rest for a couple of hours afterwards. A bath would have left me stranded in the water because I couldn't get myself out, towel myself dry or bend forwards to wash my hair.
Actually having a shower wasn't fun - the water hurt my scalp and skin. Every pair of shoes hurt my feet. Socks hurt my legs. Bending down to put socks and shoes on hurt and left me needing a rest.
If anybody were to touch me, I'd recoil in horror. A simple medical examination left me feeling beaten - one slightly too enthusiastic press of a thumb on my shoulder joint meant I couldn't use my arm for three months and couldn't sleep on my back or that side ever again.
Bright lights and loud noises drove me nuts. I couldn't cope with the TV at all and, if there were two sound sources going on at once, such as TV+Radio in another room, or TV+somebody talking to me, I couldn't hear either properly.
On the occasions I had a bit of clarity, I was snappy as hell with anybody correcting me, saying something was x when it was y or misunderstanding what I had said. If, through the fog of pain, nausea and dizziness, I had managed to make plans and organise things, if they were altered, criticised or in even the slightest way changed, I'd go ballistic. I could not cope with it - I gave every scrap of physical, emotional and mental energy into getting through the day at work.
Crappy phone games required zero physical energy and allowed my brain to switch off from the unremitting slog. So I could theoretically play them for hours.
The flat was a mess. When it took every last drop of determination and strength to haul myself 1/8 of a mile uphill from the bus stop and up five flights of stairs to my front door at the end of the day, I wasn't going to be doing the washing up, putting clothes away or wiping spills up.
After a few days/weeks/months like that, I wouldn't be able to muster up enough energy for a coherent conversation. I'd be baffled why anybody would want to stay with me - hell, I'd leave me if it were possible.
Oh, and as far as I was concerned, in addition to my 'real medical condition' that could be verified by blood test, xrays, scans and by simply looking at me, I now had a fictional illness that people used to justify their hypochondria. I was seriously pissed off to find out that what I had been taught to believe by my ex/mother/various GPs/politicians/random people in the media was 100% wrong and it was a real thing that I couldn't get over by the power of positive magical thinking, changing my diet, taking vitamins and going for a jog. I hadn't been a dick to anybody publicly, but privately I had thought they probably needed help with their mental health to be able to cope with life and then they'd start feeling better. The universe has very elegant ways of telling you that you've been a complete dick sometimes.
tl;dr Fibro causes pain. Real pain. Real headaches. The sort of tiredness and pain that is normally associated with bad flu. And no amount of sleep can ever be enough. So it's fairly understandable that somebody with it can be grumpy, 'lazy' and snappy and doesn't do physical contact if they can avoid it [memories of the pain caused by people insisting upon shaking hands, putting a hand on my arm or shoulder or, worst of all, hugging me are very strong].
I'm lucky. The symptoms disappeared almost overnight. I'm still not sure whether the shiatsu treatment I tried the day before actually did it (it was a charity five minute thing that the woman decided she would do for 45 minutes for no extra charge as soon as she touched my back - and it really hurt for most of it) or whether it was pure coincidence - but I never want to feel that much pain, sensitivity, dizziness or confusion ever again.
I'll take a flare of Psoriatic Arthritis over Fibro any day. Including any steroid injections directly into my joints.
That's why your wife is so 'grumpy'.