Without good relationships, you cannot have good communication and cooperation.
An essential point to remember is that in every communication between people there is both a relationship element and an information element.
Each person involved processes the information being exchanged through the filter of the nature and context of the relationship between the parties.
Think of it this way. How likely are you to truly listen and be engaged in communication with a colleague if you don't like, trust, or respect them?
Similarly, imagine saying the words "that was dumb" to someone you know well and have a great relationship with, as opposed to saying the same thing to a stranger or someone whom with you have a rocky workplace relationship. Whether the words are taken lightly and laughed off or they become the catalyst for an explosive confrontation is highly influenced by the nature of the relationship between the people involved.
The solution to avoid and overcome this barrier to effective communication is to be intentional in the habit of continuously nurturing your personal and professional relationships, with the object of laying the essential relationship foundation for productive communication in the future.