This is excellent advice. However, finding that out through the crucible of running a business has the added peril that both your relationship and your business will fail at the same time.
My parents owned and ran two businesses together, but they never got rich. But it wasn't a bad way to live, and they definitely saw more of each other than they would have with day jobs. Though to be fair, they also had my dad's retired pay from the military, which mitigated a lot of risks and meant they'd never be truly broke.