Songs about loving someone who doesn't love you back?

I fell in love with a girl a few years ago, and although she doesn't feel the same way anymore, I cant fight my feelings. She was my first love, and I feel like I wont ever love again. I cant muster feelings for anyone else, because all I think about is her. I'm looking for songs that describe loving someone who you cant have/doesn't love you back etc. Stuff along the lines of A Day To Remember, Mayday Parade, Coldplay Etc. Nothing earlier than like 2003 please! Thank you