Just not happening for us

I go through this every month but just need to vent again. We did everything right. BD at the right time. Was hoping and praying finally to see that double line. Again a dissapointment. AF shows up a day early just to rub it in. I don't get it, we are healthy and exercise and deserve this! Why isn't it happening !!! Ok rant over, I just had to let out some steam.