I love him but i dont really know what to do?

i miss him, but i just cant talk to him.. i see him and hes so happy, it seems like he looks at me sometimes but i dont really think he is.. we havent had a real convorsation in months and he seems so happy with other girls and im worried that if we start talking again, im just going to ruin his happiness if you know what i mean... its hard to explain.. i just really need help, what can i do?