Because Jesus loved his followers, he was able to level with them, to be candid and forthright with them. He reproved Peter at times because he loved him, and Peter, being a great man, was able to grow from this reproof. There is a wonderful verse in the book of Proverbs all of us need to remember:
“The ear that heareth the reproof of life abideth among the wise.
“He that refuseth instruction despiseth his own soul: but he that heareth reproof getteth understanding.” (Prov. 15:31–32.)
It is a wise leader or a wise follower who can cope with the “reproof of life.” Peter could do this because he knew that Jesus loved him, and thus Jesus was able to groom Peter for a very high place or responsibility in the kingdom.