I used to compare founding a company to getting married--that is, until I actually got married and learned that starting a company is far more complicated.

The process of marriage is straightforward, at least: You meet someone, get to know them, and vow to spend your life together.

But founding a company can become a mess as you add employees and investors and experience ups and downs. What begins as a promise between a small group of people becomes diluted as each person pursues a different path in the same company.

Success doesn't make these relationships any easier--just look at the bickering founders of Twitter and Facebook. But there are ways to avoid the infighting. Here are three reasons founding teams don't survive.

1. They Never Dated.

If you're going to spend months getting to know your significant other, shouldn't you be spending months getting to know your co-founders?

Yes, you want to find talented people who are passionate about the same problem. But more importantly, you want to first make sure that you share the same beliefs, values, and interests.

Companies can take a decade to build, so if your co-founders don't share your interests, you likely won't survive longer than it takes to solve the initial problem.

The best way to "date" your co-founders is to work together at an existing company or on a side project. As you do, you'll want to make sure your styles are similar, your skills are complimentary, and your vision for the company is essentially the same. There is no substitute for hands-on experience.

2. They Never Shared Their Feelings.

Sharing feelings is awkward, especially among business partners. They often get so caught up in talking about the business they lose sight of the personal connection.

What happens over time is that these relationships become less personal until both of you no longer recognize the person sitting across the table. What adds to the disconnect is the refusal to admit when the relationship is no longer working, because the only solution is for someone to leave.

Unlike a personal relationship, the business will go on without you, which is a terrible thing to experience.

That's why you have to spend time with your co-founders outside of the office. Think of it as a designated "date night" when you can discuss the state of your relationship. Sure, it may sound ridiculous, but you have to be willing to talk about why you are happy, sad, frustrated, or excited.

And like a successful marriage, a successful partnership takes hard work. So the better you learn to communicate, the more successful you're going to be.

3. Their Roles Changed. 

Over time, founding roles are going to evolve. The skill set needed to get the company off the ground will become very different as you progress from being an idea to a startup to a company.

The reason this transition is so hard on founders is because it represents so much more than a change in job title. Deep down, it represents an emotional transition, from something you fiercely controlled to a wave of momentum you simply can't stop.

The truth is that every founder wants to have a seat at the table and when that no longer happens, it can splinter relationships that once seemed unbreakable.

Getting past this point requires all of the founders to be incredibly self-aware. They have to constantly evaluate themselves as they think objectively about where they can add the most value to the organization.

Hardest of all, the founders will have to enable one of them be the leader. At the end of the day, one person has to make the tough decisions, and to be successful they'll require unwavering support. If that founding team won't provide it, their idea will never become a company.