Falling in love at 18 with someone in the military? how hard will it be to make it last?

we have been dating for 10 months and are very in love and we get a long very well each other. Both of our families approve of each of us and I am close with his younger siblings. Although I know its only been 10 months cant imagine me dating anyone else and neither can he. Problem is he leaves for the army in june for three years and will be getting out when I am a junior in college. My friends tell me I should just let him go once he leaves becuase its not worth the heartache. But I think that would be much harder on me and him. Like a lot of men in the military he someday wants to get married in the military at a young age so that he can help me pay for college and i could get other benefits. I really wish things could work out and we stay together. what do you think the chances are?