"Building the heart of" is an antonym for the phrase "breaking the heart of". It means to create love and feelings of positivity in others. To "build someone's heart" is to offer kindness, support, and affection, creating a sense of happiness and fulfillment within them. Other antonyms for "breaking the heart of" include "mending the heart", "healing the heart", and "filling the heart with joy". These phrases all imply a positive and nurturing experience, rather than the devastation caused by breaking someone's heart. By embracing these antonyms, we can focus on promoting love and positivity in our relationships, rather than causing harm and pain.