one of the partners ... willing to stand half a step lower

That's a great description of why my wife and I have adopted The Dictator Principle for joint projects. The principle is just that someone must be The Dictator and, as the project leader, must be ultimately responsible for all decisions. Being ultimately responsible doesn't preclude delegation but it does prevent conflict arising from, e.g. "I thought you were going to do that! I thought you were going to do that!".