Just like couples, co-founders fight too. As long as there are two or more people in a team, conflicts will most definitely occur and someone is going to be unhappy. In some cases, co-founder conflicts can kill the startup.
Be A Solo Founder
This seems like an obvious way to avoid disagreement, and it has been proven to be an effective one. If you ask experienced entrepreneurs whether they want to start their company with someone else, they probably will say "no", because they know that it will make things complicated. Making decisions on equity distribution, media exposure, business plan, and revenue generation models can easily trigger disputes between co-founders. Each co-founder has their own personality, life situation, and vision for the company. Some are easy to get along with, some are not. Some want to get rich quick and exit, some don't. Instead of getting into constant fights with a person you don't like, you might as well start your own business and follow your own pace. On the other hand, one can spend months or years working with someone until you really know and trust them and are sure that you're aligned. That said, there are also downsides to solo founding of your company. VCs usually like a team of entrepreneurs instead of a solo founder, because different co-founders can handle different aspects of the company's matters, and that is essential for the growth of the company. The solo founder may get sick, pass away, or shut down the business due to personal reasons, whereas a group of co-founders can reduce risks to the future of the company and the company will continue growing under the stewardship of the rest of the team members if one were to part ways.
Avoid Starting Your Company With A Stranger
Here is a typical scenario. Both you and your friend are software engineers, and you two come up with an amazing idea and start working on it. As things get more exciting, your friend brings in someone who is good at sales and marketing or someone who is influential on your particular domain. You three start working on the project together. No one ever mentions anything about the role of this third person, and this third person thinks he is a co-founder by implication and because he wants to be one. You have never met this third person before, but you sort of accept him because he is a friend of your friend. One day, you and this third person have a dispute that seems insolvable, so you decide to discontinue the project and withdraw.
Considering that even you and your best friend can have disagreements sometimes, think about how many disagreements you might have with a total stranger. Even if he is a friend of your friend, you don't know him. Of course not all strangers are bad, but the chance to find an awesome stranger that happens to click with you is very low, and it takes a lot of effort to build a relationship. If you want to start a business with someone, at least start it with someone you trust.
Face It
Yes, it is annoying, but you will never solve the problem by avoiding it. Don't be passive aggressive, don't beat around the bush, and don't run away from that co-founder you don't like. Talk to them directly but don't be hostile. You want to solve the problem, not escalate it. If you can show your co-founder that you have an open heart and you are willing to make it work, your co-founder will probably be willing to sit down and have a genuine conversation with you. When you two actually start talking, try not to point fingers. Worst case scenario, the conversation doesn't go well and one of you needs to compromise. That is still not the end of the world. Whoever decides to withdraw can negotiate fair compensation based on their contribution. If you have tried everything but it still doesn't work out, you just move on.
Professional Counseling
There are professional counselors for co-founders. If you think there is still a chance to save the relationship between you and your co-founder, you may want to talk to a counselor. You can do this together with the co-founder you have disputes with, or separately. If your co-founder agrees to do it, then there is hope that your relationship will improve, because being willing to consult a professional is the key to success in resolving many disputes. If you have a mentor, you may also want to talk to them and share how you feel about it.
A healthy co-founder relationship will not only strengthen the leadership of the company, but also benefit the long-term development of the company. A healthy relationship between leaders cultivates a healthy company culture for its employees, and ultimately helps the company grow bigger and better.