Weary, I know where you are coming from.
My story is long and complicated, but I was very ill due to pregnancy related conditions until a few months ago (though youngest dd is about to turn 3 - it took me a long time to get over pnd and physical problems as well) and dh was a total star for all the time that was going on. We have been together for 16 years (since we were 19!) and married almost 12. We have 3 children, the last one (who made me so ill) unplanned.
Dh is tired. Tired of looking after me, taking total responsibility for the kids (while I was in and out of hospital, or having so much pain I couldn't look after them properly), tired of working nightshifts as his job demended (he gave up work 4 months ago to become a student with me and it is fab), tired of the broken nights and early mornings, tired of life, I think..... also stressed about money, as we havea big tax bill to pay in Jan and he is working locums to pay our way through college, (which we love, and he says he doesnt regret the decision to do our theology course for a minute), and he is exhausted.
I would never ever leave him, ever, as I think this is just a bit of a difficult patch when I have to do all the getting up with the kids and let him spend the afternoons in the library and go to bed early while I stay up late working. Its part of being married - a long time ago dh and I promised "for richer, for poorer, for better, for worse, in sickness and in health, as long as we both shall live ....." and thus we stick to it. This isnt actually that much of a 'worse' as I know we still love each other, there is still plent of 'loving' going on, just he needs a little more care than I do right now, just as he cared for me through my 'sickness'
We make time for each other - we have booked a babysitter (local teenage girl on £10 per evening) once a week so we can go out. We cant afford to do a lot, so we often go for a walk, or go to the pub for one drink, or sit in the car and talk. We have romantic meals - put the kids to bed and eat what we were going to eat anyway, but with candles and nice music! We have a TV and computer free night once a week to talk. Talking is SO important. We are also very commited as Christians (possibly not appropriate to you) and so we try to pray together before bed, which keeps us close as well,
Its hard, when you have a stressed and tired dh, I know. But it can work out, as I also know. No idea if this is any help to you, but maybe knowing that someone else is tired and fed up with her tired and fed up dh will help, and my story is all about that, lots of love Harrisey x