I’m sorry you’re feeling lonely. But instead of striving to make your friend understand this, make new friends. Can you meet some girls at the pool or rec center? Who else like to swim or throw Frisbees or go to concerts or whatever it is you do in the summer? Going away for a vacation might also help clear your mind. Is there a camp friend or cousin you can visit? It’s possible you and your BFF will become close again, but when you see her, be upbeat rather than letting her know you feel lost. When you want to get closer to someone, it’s better to seem less needy.