Being a programmer at a university is still a "decent job", the difference in money isn't necessarily the crucial part. Instead, try telling her you want to quit so you can become an (eventually unsuccessful) painter and then observe how the relationship is working out some months down the line.
Also, what are the odds that a modern educated self-respecting independent woman would admit (even to herself) that she quit the relationship over that bit of money? If money really was the problem, she'd still have to come up with another reason to break up. Plus, it's not clear if you were already married, that's another threshold of course. Divorces are usually many years in the making.
Of course I'm not saying this is 100% exactly what will happen all of the time (though I've seen it happen shockingly often) and you will certainly find people whose dysfunctional relationships lasted a lifetime. That's called "survivorship bias".
