Should I tell him how I feel?

There is this boy that I have feelings for. We see and talk to each other everyday and the longer I spend time with him, the more I think I'm falling in love. I always talk about him with my friends and they have seen him with me and they say that we flirt alot and that it's rather cute. He flirts back too. My thing is, he's a senior (I'm a junior) and he has plans to join the Air force net year. The more I think about it the more it saddens me. I'm thinking that I should tell him, but I'm afraid that it'll ruin our friendship or he won't feel the same....