It is just to difficult to let go. Their pictures just continue to hunt one just like that of "zoom" and the "the flash", streaming in our brain, veins and all that. A very difficult situation to say "goodbye"..Even when it seems as a must, while going, you still have to look back and that very tears of love have to run down your face and simultaneously you have to take a race back to give your last hug...
The questions now is "are you the type of person people can do that for?"