Long distance relationships

My boyfriend and I are high school sweet hearts we are currently seniors and have been together for almost 4 years we are going to different colleges that are about 3 hours away from each other by train. We are in a very committed relationship but when I bring up the topic of us doing long distance he is not hesitant but not sure it will work. He is going to be on the soccer team he is 5’0 and I’m nervous he might find someone else?