You may not be able to help it as your resentment toward someone is clearly showing. You may feel a swell of anger toward a certain person in your life and not understand why. It may go pretty deep, Sagittarius, but you can't allow it to affect the way you interact with them. You may just discover, if you give yourself some quiet time to think about it, that your feelings are flowing from some other source - and not directly from the relationship in question. By being kind to someone you feel angry or resentful towards, you are also being kind to yourself - and you are giving yourself the chance to get over it and not harbor negative emotions.