My mom told him, "No need to be sad about the family you don't have anymore. Even the happiest families' children grow up and leave the nest. Change is natural. But you'll have your own family one day, and you can make your traditions just how you like them, and you can fill your house with love just like in your dream."
But y'know, I love the family I have, and here's looking forward to the family I'll start someday.