At the early stage of an emerging infectious disease outbreak, the interplay between individual protective behavior and therapeutic resources profoundly influences the effectiveness of epidemic control. By extending the classic behavior–disease coupling framework, this paper developed a dynamic model that concurrently incorporates heterogeneous behavioral adoption dynamics and saturation effects in treatment resources. Two behavioral regulation parameters were introduced to quantify their synergistic influence on transmission dynamics. Theoretical analysis yielded the basic reproduction number for both homogeneous and mixed systems, thereby establishing the threshold dynamics of the model. Numerical simulations demonstrated that increasing the intensity of behavioral adoption significantly reduces both the infection scale and transmission risk, and can even lower ${\mathcal{R}}_0$ below the epidemic. However, if the driving force for adoption is insufficient, transmission risk in the mixed system may exceed that in a system with no behavioral adoption, suggesting that ineffective interventions could exacerbate disease spread. Under resource constraints, our results indicate that large-scale, high-compliance behavioral interventions are essential for epidemic control. They further provides a mathematical basis for designing integrated strategies that balance "behavioral maintenance" and "resource allocation".