Insistence on truth can come into play when one party practices untruth or injustice. Only then can love be tested. True friendship is put to the test only when one party disregards the obligation of friendship.
You find that being vulnerable is the only way to allow your heart to feel true pleasure that's so real it scares you. You find strength in knowing you have a true friend and possibly a soul mate who will remain loyal to the end.
But what is the good of friendship if one cannot say exactly what one means? Anybody can say charming things and try to please and to flatter, but a true friend always says unpleasant things, and does not mind giving pain. Indeed, if he is a really true friend he prefers it, for he knows that then he is doing good.
A true friend of mankind whose heart has but once quivered in compassion over the sufferings of the people, will understand and forgive all the impassable alluvial filth in which they are submerged, and will be able to discover the diamonds in the filth.