One possible antonym for the phrase "giving posy" might be "withholding affection." While giving a posy, or a small bouquet of flowers, generally represents an act of generosity or appreciation, withholding affection suggests a lack of generosity or emotional openness. Other antonyms might include "neglecting," "rejecting," or "ignoring," all of which imply a deliberately cold or indifferent response to someone else's emotional needs or desires. In contrast, synonyms for "giving posy" might include "showing affection," "expressing gratitude," or "being generous," all of which suggest a positive, warm, and generous response to another person's emotions or actions.