Because they are the ones who can do the most damage...
because we let them.
Because that's the person to whom you're most vulnerable.
because you love them you care what they think
it's not that he hits you the hardest, it's just that you would never expect something like that from him, so it hurts more :)
Because it might never happen ....because of their other commitments
Figuratively speaking? Or literally?
It hurts the most because you care the most. If somebody else had done the same thing you probably wouldn't take it so hard