My bf is leaving to the Airforce(i need some help please)?

My bf is leaving to the airforce and ppl r telling me that a lot of people who r in a relationship usually dont last.And they are scearing me tht he's going to or possably cheet on me. Im want to know if ishould be concerned about it?...I truly do love him,but im just so afraid to lose him.He has been my hight skool sweet heart.And we have known eachother 4 about 6-7 years already.And we resently started datin last year in April.what should i do?