I feel you, I really do. DH and I are having a nice, quite Christmas, and our DC and their partners came around for about 3 hours, (on Christmas day,) and we exchanged gifts and had snacks and a little walk around the village. Then they went home to their respective houses - both within 25 minutes drive, and DH and I were alone again. Both sets of parents died some years ago, and we have no grandchildren, and no small nieces or nephews. One sibling each who live a long way away.
I have a bit more extended family but they live 100s of miles away - or abroad, and we rarely see each other. There's just a couple of elderly aunts, and a couple of middle aged cousins we see a few times a year, (who live 80-ish miles away...)
So there are no more big Christmases with lots of children, with parents, and aunts and uncles and cousins, and siblings, and grandparents all living within 15 minutes walk, like when I was young (1970s and 1980s.) And no more cosy Christmases with small children all excited for Santa... (and their grandparents/our parents to visit...) It's all in the past now, and my heart is full of nostalgia, for a time that used to be, when I was a child/young teen, and when my DC were. (They're 30-ish now..) I am hoping some of the magic returns when (if) we have grandchildren...
Don't get me wrong, we have a nice Christmastime, and enjoy the festive period, but I do have a little tinge of melancholy when Christmas Eve Eve, and Christmas Eve comes along.