You meet people in school not thinking of what the end result will be. The eventual parting of people you've grown close to and others you will be happy to see the back of. But after school you realise you won't be seeing some of these people again. People are moving on and taking the next step in their journey. For some people that next step will be bigger than others. Some people move to other countries and others move into a trade and others go into college.
The Summer after the Leaving is probably the harder of the Summers one will face. One makes great friends in secondary school, people who you've shed a tear with over something. People who have shed a tear on your shoulder. The people who have unforgettable quotes and traits. The people you seemed to have grown close to. But now with everyone moving on, doing their own thing it's hard not to feel somewhat emotional when it comes to saying a goodbye for a probable forever. Some of the people who will be moving to another country and may not be back. The people who you have spent a great deal of time with. These are the goodbyes which are the hardest.
Maybe I'm sensationalizing the situation, or even exaggerating it. The world is a smaller place now than ever has been. Communication and technology has greatly developed over the last few years (as mentioned in the Death of the VCR post). Being in contact with your friends over MSN and Bebo and other social networking sites is nice, but it never ever beats a good old fashioned hug.