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.
If your main concern is only about successful ones businesses then I'm not on that list but I do have partnered with my friends in Web Mastering (making websites and flipping them). The main advantages are, the workload and investment load are divided which eliminates half of the worries and tests a person's mind, There is a saying "You should eat with that person". This might give you an idea of his behavior in hunger, like is he thinks about himself or for you.
We were 3 friends and started a business together (same aforementioned), I was the main character as i have more knowledge, i started to give them tasks which i don't like because we were partners, not a company in which i am their boss i, talked with one friend and asked him what you say on this, he shared his thoughts and then the other one does the same. They always replied, do as you wish we will follow you. And i don't like that. Well, time passes and one of them was not showing interest as he was already doing another job and i know he got less time so i already had an idea how much time he will give but he was not as devoted to our work as he was devoted to his. So, i took him as uninterested.
Well, the thing is, when you are in business with your friends you can talk your heart out and tell them the feelings you are getting from them. Well due to this business other 2 quarreled and now they don't talk with one another if they have to convey a message, they pass it through me (i was a middle man) which i also not liked.
So overall, if you want to partner with friends then only do with one not with 2 or more because this could cleavage your friendship over time. Which you may also not like.