Probably too young to really contribute... but in my limited time of existence I have learned that relationships come and go... friends come and go... the only thing constant is change.
It's up to you to take from these changes something good that can improve you as a person. We'd all like to find that one person who can be our 'constant' in an ever changing world... I'm not sure if such a person exists...
Even if such a person does exist for each of us... we have to filter out those that do not contribute to our personal growth from those that do... That will always be top priority --- even more so than finding someone we can spend the rest of our life with... it might even be a contributing factor to increasing the odds of finding such a person.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen