The current global traffic situation, especially in densely populated urban areas, faces severe challenges, including significant economic burdens and environmental impacts. Carpooling, where multiple riders share a single vehicle traveling similar routes, has emerged as a crucial component of sustainable urban transportation by enhancing service efficiency, reducing operational costs, and minimizing environmental impact. However, many studies overlook the diversity of human needs, vital for improving urban quality of life. Our model addresses this by introducing destination flexibility, allowing more efficient matching of drivers and riders through shared destinations for intended activities. This approach assumes that individuals with pro-environmental attitudes or cost-saving preferences are willing to adjust their destinations to share rides. Simulations demonstrate that this strategy significantly reduces path costs and improves route efficiency. Additionally, we propose an optimized fare calculation method that ensures fares accurately reflect actual travel distances and detours, distributing the carpooling costs among riders. This paper highlights the potential of this model to contribute to more reasonable and efficient carpooling solutions, promoting sustainable urban mobility.