Parents have an uneasiness about their children when they are separated from them. That uneasiness does not go away or even diminish the older the children get; it, in fact, increases because the separations are longer and potentially more consequential. There is an uneasiness about Proverbs 22:6, the "white space" (of time) between "go" and "when he is old." Job knew this uneasiness of separation concerning his grown children (Job 1:2, 4-5).
Our Father in heaven hates the separation between Him and His beloved (Is 59:1-2). So much so that He paid the highest price possible to remove that separation (2 Cor 5:17-21). The Father has done EVERYTHING He can do to abolish it.
Be comforted, parents of grown children. Our uneasiness is but a mere shadow of what is in our Father's heart. He knows our discomfort. He is showing us His heart. He is our Comforter. He is also the Father of our children. Be still, and know that He is God. And pray (believing) without ceasing for our grown children!!!