Reminds me a lot of graduating from high school.
You spend 13 years with one group of people, you're going to have ups and downs, and you're going to witness other people's. It doesn't matter if you're close with everyone; you've been through it all together. You may not like everyone, and there may have been people that you've had major differences with. At the end though, all the little things that happened over the years really don't seem to matter that much. You get to the end, look back, and see how far you've come together. Then you can look to the future, and see that there's still a long way to go. Maybe you won't be surrounded by these people anymore, but you've come this far and that's all that's really important at the moment.
Reminds me a lot of graduating from high school. You spend 13 years with one group of people, you're going to have ups and downs, and you're going to witness other people's. It doesn't matter if you're close with everyone; you've been through it all together. You may not like everyone, and there may have been people that you've had major differences with. At the end though, all the little things that happened over the years really don't seem to matter that much. You get to the end, look back, and see how far you've come together. Then you can look to the future, and see that there's still a long way to go. Maybe you won't be surrounded by these people anymore, but you've come this far and that's all that's really important at the moment.