The ones we hurt are the ones we love the most

yep. the ones we love have high expectations of us and when we dont meet these expectations,they are hurt.
if a stranger was to insult you,itd hurt, but if a loved one was to insult you,itd hurt hell of a lot more! reason being that you have a connection,a bond with the loved one,so what they say/do to you means more and is important to you cos you care about their opinion etc more than you would a stranger.