The antonyms for "more stony-hearted" could include "compassionate," "empathetic," "sympathetic," "caring," "kind-hearted," or "tender-hearted." These terms describe individuals who are sensitive to the feelings and needs of others, and are often willing to go out of their way to help others. Compassion and empathy are key qualities in building strong relationships, and in promoting social harmony. In contrast, being "stony-hearted" or lacking in empathy and compassion can lead to interpersonal conflict, isolation, and poor mental health outcomes. Therefore, it is important to cultivate compassion and empathy towards oneself and others, to promote positive interactions and wellbeing.