I'm with gness on this.
I have three daughters and although they have not gone to university, they have all moved out of home, and subsequently married and had families.
The relationship is different, but that is not a negative thing.
The dynamics shift - your children become adults in their own right, with their own lives, and your relationship with them shifts accordingly.
As gness says, you get drawn into their social lives, and meet new people.
But fundamentally, a mother's children are always her own, that never changes, and that link remains unbroken, which is as it shouldbe.