“Friendship is a strong and habitual inclination in two persons to promote the good and happiness of each other.” – Joseph Addison
True friends promote both the good and happiness of each other, not just the happiness. As such there is occasionally the need to communicate hard sayings, counsel which would likely offend in more superficial relationships.
True friends give and receive such guidance with an open heart, even if the matter being outlined is not clearly or fully understood by one of the parties. If a friend is offended by a call to greater goodness, then he in that moment faces a uncertain future.