Tensions occur between people. They manifest in our daily life in different forms, from subtle sensations of discomfort all the way to emotional outbursts. Have you noticed how often conflict of interests are at the root of those tensions?
Next time you are in a situation where you notice some tension between people, try to analyze it from a "conflict of interest" perspective. You will at least get two benefits out of this: a better understanding of other's point of view and avoiding the risk of speaking and just being blunt, as you will be busy thinking. Give it a try.