Try to treat it as one of life's inevitable disappointments and envisage some worse situations that might have occurred instead, like being diagnosed with cancer , being involved in a road accident and permanently crippled, losing your job or your home or your life savings, or having a much loved member of your family die suddenly.
It's hurtful, but not the end of the world and almost certainly in time somebody else who appreciates you more will come along to fill the void.