I spend a great deal of time, more than on any other concept, drumming it into my students heads, relationships are critical to your success.
There is value in knowing who we are and where we are going, but it is of equal or greater value to know who travels with you and what their goals and agendas are. It is difficult to establish a personal relationship between 2 people who have the same goals emotionally, in life, and personally. It is more difficult to establish a safe, secure and productive relationship on a business level, whether long term or short term.
If this sounds strange, stop and think about the magnitude of the relationship. You  both agree that it is important for the project to be successful, but that goal is harder to reach if you are only invested in the project instead of being invested in each other. The relationship is built on only a sense of professional courtesy and propriety. When we focus only on the project, its success becomes tied to our own success, our ability to showcase our work, and to continue employment.
Creating successful relationships in any project is paramount to the success of that project. Those relationships set the tone for the project and the attitude of the team as a whole. Managers are responsible for the success of those relationships. That being said, we can’t just direct all parties to get along. We can, however, set the right example through our actions with all team members. We can accomplish this through personal interactions with each member and, maybe more importantly, by the tone we set with individuals and the group in meeting and group communications.
Anyone can learn to schedule and budget, not everyone can learn to manage relationships.