50/50 sounds fair, but it kills decision-making. 60/40 or 70/30 reflects reality if one founder started earlier or commits more.
Decide based on: time, money, idea, network, risk taken. Use a tool like Foundrs.com to weight inputs.
Decide before you have anything to fight over. Document in writing.
Next action
Turn the lesson into work.
Pick one concrete next step now, while the context is still fresh.