I Sometimes Feel Lonely

All I ever wanted was someone who I cared about to love me back and want me back. It seemed like it might happen a couple times but never lasted and always takes a chunk of my heart with it. Takes part of me with it killing me. I don't know why it's so difficult to get someone to love and want me back. Time has shown that I am a wonderful friend and lover. Why do they always leave. I don't get it. Humans suck.