Dude, I think this "skill" is probably something learned. I, unfortunately, don't have this ability, either. I'm going through a breakup and it seems like my ex has a heart of stone. She's moved on and I'm left in the dust. It hurts so darn bad that sometimes I just want to end it, but I wake up and smell the coffee, knowing she's not worth my life. Anyways, I hope that in time you can learn how to move on, as I wish this for myself, also.

Good luck!