 Why does Ben tell Laura his has her wedding ring?
How can I tell you what it's like to be young and a man and to dream of reaching the stars? They're going to bring us the metals and minerals that we desperately need. They're going to find new land for our colonists, good rich land that will bear food and be a home for our children. And perhaps most important of all, they'll make other men think of the stars and look up at them and feel humility—for mankind needs humility." Mickey Cameron, sitting next to me, dug an elbow into my ribs. My parents had died in a strato-jet crash when I was four, so I hadn't needed many of those "You are cordially invited" cards. Just one, which I'd sent to Charlie Taggart. I remembered how, as a kid, I'd pestered him in the Long Island Spaceport, tagging after him like a puppy, and how he'd grown to like me until he became father, mother, and buddy all in one to me. Though it was daytime, I saw the stars in my mind's vision, the great shining balls of silver, each like a voice crying out and pleading to be explored, to be touched by the sons of Earth. "You made it, boy," he chortled, "and by Jupiter, we'll celebrate tonight. And you, Laura, were with him. Charlie gulped helplessly, and Mickey said: "Still going to spend the weekend with us, aren't you, Ben?"
 Ben is telling her that even though he can't stay, she is the only woman he'll ever love.
 Ben is telling her he can't marry her, so he's taking back the ring.  Ben is telling her that even though he can't stay, she is the only woman he'll ever love.  Ben is telling her that the marriage is over, so he's taking the ring back.  Ben is telling her he was going to marry her but, she can't compete with the universe.