We spent last weekend with our daughter and my parents at her college. For me at least, it was strange. Seeing her as her own person, making her own decisions and charting her own path apart from us. Everyone who has kids in college goes through something similar. The child you invested 18 years into raising so you could get to this point, now it has happened, now they're out of the house. Now there's that strange void where they used to be. It's different when they're away for the day at high school. You know they'll be back later in the day. Now it's stretched out to weeks at a time, maybe months, with just a phone call every so often. And all you can do is wait, and adapt.
But they are standing on they're own two feet. Your parenting role is different, you are the sideline coach, still important, but in a different way. There's still memories to be made and fun to be had. And a wonderful future to look forward to.