in a sense it's karma. you loved and adored them so much but they broke your heart and caused you pain. now they have to live with that pain and regret. that they held something precious in their hands and then they dropped it.
i don't know if i'll ever completely get over my ex. i think he's always going to be that one ex i'll always hold a candle for... but if he came back i wouldn't 100% adore him anymore. He let me down in a big way and once that trust has crumbled it's hard to give your heart into their keeping again. It's hard to feel safe when all you're going to be listening for is the other shoe to drop.