Take the job.

Allocate a portion of the extra earnings to hire a cleaner once a fortnight.

I know for me that I am a much, *much* better wife and mother when I am fulfilled. Not selfishly running around doing everything I please, but genuinely fulfilled, with a challenging, rewarding, personally growing career that I love and am good at. Something where I make a significant contribution directly into the lives of others, and which in turn feeds, blesses and nourishes me.

So I would go ahead with the job, and let my DH see the fruit - a better me, and therefore a better wife and mother.

If there was some genuine reason it was going to drive a wedge in my marriage, I might think twice - but if the wedge was going to be driven by my career choice (and something which I'd already studied and was working towards, and which had a perfect opportunity arise) then a wedge would just as likely be driven by resentment, if I had to pass up my dream job because of some extra travel and a bit less cleaning ...

Generally speaking though, I expect household tasks (cooking, cleaning, laundry, gardening) to be allocated equally with adjustments as required (someone's working much more, or studying for exams, or sick, or whatever ... but generally, it's pretty equal...).