The only ones that can hurt us are the ones we care about.

Absolutely true!  

I agree with steve

Then it is a bad thing when my best friend betrayed me  I felt nothing and it is so hard to even remember his name.  Do you think my mind just blocked all possible memories so I wouldn't feel anything?  But all I know is he avoids me like...well...he books it in the other direction whenever he sees me. Even this I have to struggle to notice.