Conservation science has made extraordinary progress in documenting the ecological systems we are losing. It has made far less progress in understanding the human affective systems that determine whether those ecological systems will be protected, restored, and sustainably governed over time. This paper introduces Eco-Affective Health as a theoretical framework and proposes six testable hypotheses for understanding the affective dimensions of human-nature disconnection and reconnection in conservation contexts. The framework rests on a foundational reorientation: emotions are not downstream reactions to ecological conditions but constitute the primary regulatory mechanism through which humans perceive, interpret, and respond to the living world. This positioning generates specific, empirically testable predictions about how eco-affective states, including solastalgia, soliphilia, awe, ecological identity, place attachment, and collective efficacy, shape conservation outcomes across individual, community, and governance scales. The framework introduces the solastalgia-soliphilia axis as a diagnostic and enabling tool for conservation monitoring, conceptualizes affective tipping points as analogues to ecological early-warning signals, and proposes the Symbiocene as a health-oriented evaluative horizon for conservation decisions. Three integrated tables map eco-affective constructs to testable predictions, formalize six falsifiable hypotheses, and translate the framework into a proposed expansion of conservation monitoring systems. The paper argues that the social feasibility of conservation outcomes, the durability of stewardship across populations, and the legitimacy of conservation governance all depend fundamentally on affective infrastructure that conservation science currently lacks the conceptual tools to measure, design for, or predict. Addressing this gap is not a theoretical nicety. It is a prerequisite for conservation science adequate to the scale of the biodiversity crisis.