Antonyms for the phrase "more tender-hearted" would include words such as callous, unsympathetic, unfeeling, and cold-hearted. These words describe individuals who exhibit a lack of compassion, empathy, or sensitivity towards others, often displaying indifference or cruelty towards those in need or distress. They are the opposite of those who are tender-hearted, who are characterized by kindness, warmth, and a deep sense of empathy towards others. While some may view tender-hearted individuals as weak or overly emotional, their capacity for understanding and compassion can have a significant positive impact on those around them.