Should I stay with him

My boyfriend of 1 year is planning on doing FIRSTPOINT USA FOOTBALL COACHING. He has to leave the U.K. And stay in America for 3/5 years! Coming home at summer, and Christmas. I'm at uni at the minute and we would both finish at the same time. He's said since day one he's doing this to better our future and future family. I don't know how to deal with this:( it's killing me just thinking of him going. He wouldn't leave for another 2 years. Planning on getting engaged next year :(  Help!!!!