It is always difficult when the target of our romantic affections are unwilling or unable to return them in kind, and it is always harder when they are somepony already close to your heart even before physical attraction and romance are introduced. It saddens me on your behalf to know that you had to learn this lesson in this way, but it is very important to realize that our first loves rarely work out as we would desire, and the objects of our first desire rarely satisfy for long.