Many years ago, I heard the story of a man whose business partner did dirty. They were business partners for almost 5 years and the suddenly the business partner left with company's money. Even after several years, this man didn't recovered. He ended up sounding it as a warning to his kids never to go into business with anyone. The trust was destroyed and never recovered. This is just one of those sad stories.
On the other hand, there are many success stories of friends who went into business together and succeeded to together. If you have ever gone into business with a friend, what were your biggest concerns and how did work through it.
How long have I known my friend? What are their thoughts on money? What would he think if he had too much money? Establishing trust is not an easy thing. But once it is achieved, things get easier. How does he treat his family? How does it approach the environment? All these questions are questions that should be asked beforehand in order to do business with a person.
I wouldn't start a joint venture without getting the answers to these questions.