I was an early employee at start-up where the co-founder relationship was 50/50 and looked very much like this. They did their best as time progressed to keep tensions behind closed doors, but the company was small and it became clear that while co-founder "A" was giving lip service and was completely disengaged, co-founder "B" was getting things done and providing effective and actionable feedback.

It was clear that "B" was doing both of their jobs and was burning/burnt out. That is simply not maintainable.

In the end the company was acquired, allowing them to go their separate ways. "B" and I have remained friends and I could almost hear his voice as I read this article! I look forward to seeing what he does with those hard earned lessons applied to his next company.