It's a development rooted in trust, not just love. He learns to trust Serenity's consistency, to trust that she won't weaponize his vulnerabilities, to trust that his feelings won't be used as a leash. This foundation of trust is what allows his love to grow securely. Without that trust, his love would have remained a frantic, anxious thing. The steady, daily building of trust is the invisible scaffolding for his entire emotional arc.