First off, there are multiple types of arthritis.
If it is osteo, then the pain can be a bit much and it can be tiring. But if it as an autoimmune type of arthritis then the fatigue can be totally and utterly debilitating. It may be that not only was he not physically able to put food in the oven, but that he could not do it safely.
I have psoriatic and rheumatoid arthritis, lupus and other health issues and am bipolar. This is an ok time of year for my joints as its warm, but a terrible time for my bipolar as its sunny 18 hours a day. I have terrible days for both and do my best to juggle 3 children between 9-17, studying and the house etc. I do ok. My house is never going to win any show home competitions but that's fine. My fridge freezer is full and my kids can all cook beans on toast/micro-meals etc.
Last night I was invited to a bbq with my youngest. I went. My husband had to collect me as my car had a flat so I had a few glasses of wine. He turned up at 8 and moaned very loudly that I should be at home cooking his and the eldest two kids dinner. I burst out laughing. I killed myself traipsing around Aldi, iceland and farmfoods filling up the fridge freezer, why on earth would I , a person with several chronic health issues, need to be there to cook beans on toast for 3 fully able people? me and my youngest had already eaten. Yet my 50 year old husband suddenly felt he was incapable of turning the cooker on and as I "stay at home" it was my job. I do what I can, and that is it otherwise it is on time stolen from tomorrow. Thankfully he is not like this 99% of the time but will be getting a very stern talking to when he gets home and if he does not like it he can sling his hook.
But you are healthy, work very little and seem to think he has limitless energy. batch cook and freeze stuff for emergencies, I do and I study PT, work PT and run a house and 3 kids. I really do not get your OP when you know he is ill and working full time, he is bound to have bad days!