Am i to young to stay committed to a marine?

heyy well heres the deal, should i wait 4 at LEAST 3 years for my boyfriend to come from tghe marine? im only 16 and hes already grad. am i to young to wait for him? he wont be able to come to any of myevent including prom. we have been datin almost 4 months and i really really care for him. and in 3 months hes goin to be gone 4 years.... i told him ill wait and ilh but now im scared... what if somthin happens to him? what if i find someone else y hes gone? idw to brake up with him while hes there bc what if it distracts him and he gets hurt? really kinda upset. i dont plan on meeting anybody. i plan on bein faithful, iv nvr cheated or anything but its just the idea that for years im goin to be alone... he said when he comes bak he wants to marry me and we can really start our life. whats yalls thoughts?