Why does love hurt so much?

We all want it, crave it and NEED it; so why does love hurt so much?  Being vulnerable with someone else is a scary thought; however, it's one of the main ingredients for intimacy and love.  Thus, why are we intuned to chase something that can really hurt us?  

I want love to be wonderful, exciting and rejuvenating!  I want to know how to love someone without hurting them.  I want to feel loved by those that I love so dearly.  Yet, at the end of the day, all I seem to remember is how much she hurt me when she took my heart and crushed it.  I know she's just as scared of getting hurt.  We try and try to soften the blow, inevitably when it comes, but the heart sick feelings never really go away.

I'd rather be her friend than to not have her at all.  That's what I tell myself.  I've pulled away, licking my wounds, but she's still with me in my heart as if she refuses to leave!  I just want to know if she still loves me; not knowing is worsening my state of mind.

I never knew how much a heart could hurt until she told me she loved me; knowing that we'd never have a chance to be together.