If you establish arms-length relationships based on contracts describing the expected results rather than the nature of the relationship then each party will work for its own short-term gains, and the relationship is likely to break down over time as goals diverge, motives are questioned, and communication becomes forced.
Nurture cooperative partnerships for the long-term that are built on mutual loyalty, trust and confidence, and which share the risks and the rewards. Treat your partners as extensions to your business and align incentives so that everybody works for the good of the partnership.