I definitely agree with the advice to seek therapy for the inevitable relationship issues over coaching. Coaches definitely will help the individual but the experience is typically so one sided that it can often result in making tensions worse. A co-founder leaving can cause a lot of trauma to organization that is impossible once one leaves. I'm sure founders think the main impact is individual but let's be honest, it affects the entire staff. So yeah, co-founder tension needs to be treated like a marriage for the benefit of the co-founders and especially the benefit of the employees.