The key to most financial instability is underlying mental instability. I should know. That is why so many artists starve; It's nature's way of weeding out the ones who are not attractive enough to be parasites or savvy enough to make salable products.
I am speaking as an artist, mind you...
When it comes to longterm relationships with the mentally unstable, they always hold danger. Financial stability might mitigate against it harming the partner, but even that is not guaranteed. Nope, mental stability is better for longevity.
OTOH how can you truly guarantee that anyone is mentally stable? The very definitions of that are highly subjective and vary in every culture. I was extremely hurt by my ex's constant hounding of me to do things the 'normal' way. What he really meant was HIS way. My ways to address envelopes, do dishes, or a hundred other things broke no laws and did the job. Until we met I had never even had a parking ticket...six years in i was a chronic liar and in therapy.
Hard to say which of us should have been judged less mentally stable. All one can say for certain is that we did not fit each other.