They simply the reason to stay alive. 

And when thay hurt - they hurt my feet, not break my heart. That why it so easy for me to fall in love with them, because i can always put them in a drawer and get another pair. New pair. One who makes me to belive he is the one i want, the one i need. 

When they let me down they make me excited for the next couple, they do not cause contraction of the heart and a will to bury myself in bed with moist eyes and a sense of missed opportunity.