Love is patient and Love is kind. I Corinthians 13:4 (NKJV)
Have you ever saw a situation go from laughing to serious in a matter of seconds? Have you ever wondered, what did I miss for the situation to go sour? When you face those situations, your response at that moment is most important. Respond in love, let it go and let God fight your battles. Tell God exactly how you feel and leave the problem at His feet.
When you are kind and loving to someone when they have been mean, it like you are heaving coals of fire on their head. Continue in this fashion of being kind and loving. Then watch God change their hearts. Do not be surprised when they apology for treating you badly.