I've parted ways with cofounders in two of my five startups (they left, not me... I could afford a zero paycheck for a little while, they couldn't). In both cases we did better after the split. In both cases our original business idea didn't work out, and we were trying to stay alive. It felt like pivoting from idea to idea. Reality was it was just trying to sell and collect enough to make payroll in six weeks. So we went from whatever we were doing to custom dev shop... Survival mode sucks.
When got down to a single founder, it wasn't that one person was right or wrong about what the business could do. It was that the business could execute well enough (without cofounders fighting and second guessing) so it could survive, and eventually find something to productize.