I don't understand how I can be in love

How can it be? How can it be possible?  How can I be in love? The loner. The lone wolf. The forever alone guy. How can I be in love? Apparently I have loved her for years but never knew it until I heard she was leaving. Never again will I see her if she leaves. Never will we be able to be together. Are we meant for eachother? I think so. But if she leaves then that can't happen. How could I decide now was the time to tell her I love her?  Why did my heart decide now is the time to open up when it makes no difference? How can I be in love?