I always say "Be safe" rather than "Goodbye", but if it's ppl really close to me and I'm not going to see them for a while I get really teary no matter how hard I try not to show it, but I never really cry. It's sad when you have to leave someone and v.v. for a long time 'cause you know you're going to miss them so much; they're not going to be as close/around the same way anymore and you never know when and if you'll ever see them again. And it gets a bit difficult to actually realise that on the day you/they are leaving.
However! You have to be brave when you/they leave to help them be brave as well! You'll hopefully see them again soon so if you stay positive it'll be alright. :kaoplain: