When they are little, they have no choice but to want to be with you. They fear your leaving, crave your presence.
When they are nineteen, however, and home from college and hanging with their friends, well that is, as they say, a horse of a different color. Then, when you ask them to come with you to see another movie made in 1939 and they, without hesitation, agree and laugh alongside you while sharing a large popcorn and marveling at the assured and easy cynicism of Claudette Colbert in Midnight, well, you know they have chosen to be there with you.
And even if they then decide to forgo the second feature in favor of a party with their friends, it feels great to have been, however briefly, chosen.