The BIG List Of What Causes Co-Founder Relationships To Break Down

Last Updated: May 31, 2018. 

What is the point of this list?

I do not want you to get caught by surprise when what seems like an unrelated change causes problems in your co-founder relationship. I have talked to so many co-founders who made a change in their life, or who had a co-founder who did, and 6 to 18 months later that change is causing significant problems in their relationship. Even little changes can have a ripple effect that grows larger over time.

Where do the list items come from? Every item on this list is from a co-founder. Want to share your story? Contact me privately, or answer this question anonymously on the site here.

How do I recommend you use this list? I would love for you to just do a quick browse and realize the type of things that have actually caused co-founder relationship problems. I think that if you have a broad understanding of what has caused problems in other co-founder relationships that can help you be more aware of what to watch for.

The BIG List Of What Causes Co-Founder Relationships To Break Down

I hope to eventually add links to the stories people share on the site to illustrate the real-world examples behind these. 


  • Marriage, this is a big change for the person doing it, as well as the effect on the person not doing it.
  • An addiction growing out of control, anything from drinking to drugs to gambling.
  • One co-founder stops drinking or starts drinking.
  • Cheating on a wife or girlfriend.
  • Divorce, no matter how amicable that divorce might be.
  • Health problems of any kind, even if it is a health scare that is nothing long term but causes a shift in their lifestyle or outlook.
  • Any type of health problem with a friend or family member.
  • A death of a friend or family member.
  • A change in personal finances, or personal financial needs. This can be anything from having twins to getting married to picking up an expensive sport.
  • A life crisis of any kind that causes someone to change their goals and priorities. This could be as simple as someone who once put in 60 hour weeks wanting to only work 30 hours.
  • Underlying personality or behavior problems that don’t manifest until heavy stress or employees appear.
  • A co-founder wants to do something new and is bored.
  • A change in sexual orientation, this kind of change can cause you to evaluate a lot of things in your life and shake things up.



  • Co-founder felt the business was growing too fast.
  • Co-founder felt the business was growing too slow.
  • Co-founder felt the business should scale back and focus only on one region or country.
  • Disagreements over need to raise an investment round.
  • An investor who sides with one of the co-founders and significantly changes the power dynamic.
  • One person’s role at the company receives a lot of publicity while the other does not. This can be external or internal publicity/acclaim too.
  • One person’s role in the company grows in scope and responsibility.
  • The company grows in terms of people and a co-founder is not suited for running a team or people in general. There are so many stories of a brilliant engineer who builds the starting product, but once the engineering team grows to 5 people they can’t manage people and are hurting the company badly at a key stage.
  • You grow to a size where you hire incredible people and this changes the internal power structure of the company as they take over swaths of the business that one of you used to run.
  • VC / Investor / Angel pressure or disagreements. They can make something loose all the fun which can cause problems.