I remember this struggle with my own sons. Fortunately I had a favorite poem that helped me through some tough "letting go"times. It still does. When each of my sons left the nest I sent him a copy of the poem. I doubt either of them read it but then they weren't the ones who needed it. I did.
If you're having trouble dealing with your "About to be a Man" son flying the coop, this might help.
I HOLD THE BANDAGES AND OINTMENTS READY by Alan Paton
I see my son is wearing long trousers, I tremble at this;
I see he goes forward confidently, he does not know so fully his own gentleness.
Go forward eager and reverent child, see here I begin to take my hands away from you,
I shall see you walk careless on the edges of the precipice, but if you wish you shall hear no word come out of me;
My whole soul will be sick with apprehension, but I shall not disobey you.
Life sees you coming, she sees you come with assurance towards her,
She lies in wait for you, she cannot but hurt you;
Got forward, go forward, I hold the bandages and ointments ready,
And if you would go elsewhere and lie alone with your wounds, why I shall not intrude upon you,
If you would seek the help of some other person, I shall not come forcing myself upon you.
If you should fall into sin, innocent one, that is the way of this pilgrimage;
Struggle against it, not for one fraction of a moment concede its dominion.
It will occasion you grief and sorrow, it will torment you,
But hate not God, nor turn from him in shame or self-reproach;
He has seen many such, his compassion is as great as his creation.
Be temped and fall and return, return and be tempted and fall
A thousand times and a thousand, even to a thousand thousand,
For out of this tribulation there comes a peace, deep in the soul and surer than any dream...