The relationship between human well-being and environmental well-being is deeply intertwined. This paper explores the constructs of gratitude, nature connectedness, and social relationships to establish the scientific foundation for a positive psychology intervention titled Toward a Culture of Connection: Sharing a Love Letter to Nature. The randomized controlled study will use research on the pathways to nature connectedness by targeting emotional and cognitive leverage points for greater systemic change, addressing calls for more comprehensive, system-informed approaches in positive psychology. As we confront unprecedented environmental challenges and a surge in loneliness and mental health issues, this intervention for couples seeks to enhance both human connection and nature connectedness. Social connection is one of the leading contributors to happiness, and by fostering stronger emotional bonds and a greater cognitive understanding of our interdependence with nature, the intervention aspires to promote happiness and drive positive behavioral changes that support human and environmental well-being.