Choosing To Befriend Everyone

It’s a conundrum to me when I imagine befriending everyone. How would that even work in the law? Shakespeare’s instruction notwithstanding, how is it possible to strive to the end and then call my adversary friend? Even more challenging, how can I learn to relate to my frustration and grief with friendliness? When all I really want is for it to stop? And yet this is the path of the warrior. What a paradox.