"And the Almighty saw that Leah was hated and he opened her womb, but Rachel was barren" (29:31). Radak comments that "hated" does not mean that Yaakov did not love Leah, rather, in comparison to the love he had for Rachel it was as if Yaakov hated Leah.
Feelings are uncontrollable and tend to cause people to act in unexpected ways. One can never know how another will reinterpret an incident or comment in their own mind. Therefore, from this incident, of Leah thinking that Yaakov did not love her, Rav Yeruchem Lovovitz comments that one must be extremely careful with what one says to another about their spouse. One may be insecure about how the other feels and to cause an emotional problem between them would be an awful thing. How much more cogently should this apply to all of our friends!? Between married people there have been vows of trust and love. But among ordinary friends nothing is bound. There are good, unfortunate reasons why friends very often drift apart and we must very often look back at old lost friendships.
There is a story of a man who asked his rebbi to teach him the problem of speaking about others. The rebbi took the man to a field with a feather pillow, slashed it open and they watched the feathers disperse. He asked the man if he saw the way that the feathers acted freely and acted at random. This is what becomes of our words when they leave our mouths. We can never know in what form they will reappear in the heart of a friend, after they have been distorted numerous times. Therefore, we must be extremely careful about any comments we make about friends to others. And, by learning to appreciate human feelings we will learn great lessons about friendship and maintain all of our needed friends for many years.