People have very different personality types. If you're angry and want to talk, your co-founder may not be interested in talking right now. It's important to know how big of a deal things are when someone brings them up. Can you give each other positive feedback? And lastly, will you feel attacked if your co- founder makes a suggestion about your work?
How do you find a co-founder and build a great partnership? YC's Catheryn Li (who also built our Co-Founder Matching tool) and Visiting Partner Divya Bhat cover the importance of having co-founders, how to get & vet one, and the ways to build a successful working relationship with them.
Apply to Y Combinator: https://yc.link/SUS-apply
Work at a Startup: https://yc.link/SUS-jobs
Looking for a co-founder? Sign up for Co-Founder Matching: https://www.ycombinator.com/cofounder-matching