"Mess with head" is a slang term that refers to the act of confusing or manipulating someone's thoughts or emotions. To describe the opposite of this behavior, we could use words like "clarify," "simplify," or "validate." Instead of trying to confuse or mislead someone, we could strive to help them understand things more clearly, make sense of their feelings, or acknowledge their perspective. Other antonyms for "messing with someone's head" might include "support," "encourage," "empathize," or "listen." All of these words suggest a desire to foster positive relationships based on mutual respect and understanding, rather than manipulation or deception.