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.
Basically, trust is built from two directions. not only in business and friendship, but also in other matters including partnering with a spouse and everything must be based on mutual trust. openness, transparency and commitment. with a solidly built foundation, things that are not desired can be easily resolved if there are internal problems.
however if the opposite happens, what you describe in this thread is prone to happen. It's not easy to build a business together, especially with a friend. sometimes, the little things can be a hindrance. which in essence, before we build a business together, we first know the background of friends who will become partners or joint business partners. this is done, so that something undesirable does not happen. even then there is no guarantee, basically humans have an innate nature that is always selfish when situations and conditions are unfavorable.
By the way, I have experience doing business with some of my best friends. long story short, the business did not go as planned and expected. in the end, friendship is at stake. with this experience, I said it at the beginning of the post. so to build a business with friends, it takes trust to be built from two directions. if possible, it's best to avoid doing business with your closest friends. because usually, business will not run well. except, if it is run professionally.