Had one for five years, although it was also a mutual/loving relationship, but with benefits.

She wasn't a millionaire, but made significantly more than I did and also had a lot of perks through her job that I was able to get in on.

We split rent on a very upscale apartment, I paid for my own phone and vehicle, but that was it. She covered everything else- bills, food, activities, trips, etc. I got to travel for free through her job, they paid for spouses to go on business trips, she also had crazy spending accounts that you could buy just about anything through, expense it, and only had to pay the taxes, which she always covered.

In the end I fucked up the relationship, I did want to marry her, but I'm kind of a shitty human being and an alcoholic...so, she broke it off with me recently.