Up to 43% of startup founders ultimately buy out their cofounder due to interpersonal rifts and power struggles. To understand why so many cofounder partnerships end in failure, the authors conducted research on lead founders seeking cofounders, finding that lead founders tend to prioritize skillsets and execution while potential cofounders prioritize interpersonal compatibility. This mismatch in priorities is the root of so many cofounder splits. To overcome this, the authors offer three recommendations for lead founders and cofounders alike: 1) Put yourself in the other person’s shoes, 2) Don’t neglect the interpersonal aspect in initial conversations, and 3) Consider co-creating the idea with a partner.