Friends with older children have warned me about Empty Nest Syndrome. Forwarned is forearmed as they say.
So much as I adore our children I have always taken care to keep up with my own friends and activities. My children are the most important part of my life, but they certainly aren't the only part. Also my husband and I were together for a long time before we had children, so we had built up a whole life together, routines and rituals, which weren't child-centric. We still really enjoy each other's company and have always still gone away for weekends alone etc.
As our children have got older and into their early teens they are naturally spending less time with us. They go to sleepovers a lot, and spend whole days with friends rather than just a couple of hours. They are building their own lives, creating their own niche in life and that's exactly how it should be.
I certainly don't wait around, all forlorn, watching the clock until they get home again. That would be rather silly and also rather unfair. Children will pick up on that sort of behaviour and it will put an unfair burden on them. No child wants to feel that their parent relies on them TOO much for emotional/social support (I know, because I was that child) and I bitterly resented my Mum for it.
When the times comes for our children to go to university I certainly won't be hanging out the bunting and popping champagne corks. Inside I will sad, and that a part of my life has come to an end. But I wouldn't dream of letting my children see my sadness, and will be all smiles and full of good wishes for their new adventure.
But I have always understood that my children aren't mine to KEEP. They have only been gifted to me for roughly 18 years and they have been the very best gift ever. But I have lots of other gifts too (my husband is one of them, and friends are another) and I fully intend to appreciate them too.
Good parents give their children roots, but they also should give them wings.