I love that yoga begins with non-violence. It sets the pace for everything that is to come.
In my experience true love always comes from within, I can not love someone and stay in a relationship if I'm not loving myself first.
So by loving yourself 100% you not only make your own life better, but also that of everyone you are involved with because you can see your true self, that spark of consciousness, within everyone. So by loving someone else, in essence you are loving yourself.