Oh this is a tear-jerker! It is lovely and horribly sad. I have a daughter far away in college. It is sad, but I am lucky in that I quite vividly recall how happy I was to be free and hundreds of miles away from my parents. I remember that and I tell my daughter, "Call Grandma, or write her."
This reminds me of the last phrase of J. M. Barrie's Peter Pan: "...and thus it will go on, so long as children are gay and innocent and heartless." Well, the Golden Trio are not carefree and naive, but to do what they have to, they have to be heartless, especially Hermione. Speaking as a mother, it is so sad that the trio could not see beyond the moment, and give her mother a few more hours, especially when all three suspect that anyone of them may not be returning.