Empathy is the essential element of any relationship, be it with a friend or a foe. With a friend, it is the key to communicating your heart. With a foe, it is the key to predicting their action. The power of empathy is underestimated.
In the great spiritual texts, love is emphasized, but it is empathy that enables authenticity. Love without empathy (for your friend or your foe) is discipline without emotion. There is a place for such discipline, but I am suspicious of it. When I can feel what the other person feels, I am able to care in a way that empowers genuine understanding.