Think about what you want, what you want to risk, and what you can live with. If after thinking it through you still aren't sure, throw caution to the wind and tell him how you feel, and ask him if he feels the same. Worse thing that can happen is he doesn't feel the same and you are friend zoned. That would be hard but at least you would know and you could then find another boy. Best case is he feels the same. You probably should consider doing something though, because it is causing you some strong emotions seeing him with others.