To love someone enough to let them go, you had to let them go forever or you did not love them that much.
(Diana Wynne Jones, Fire and Hemlock)

When will I be yours? When will I be mine?
(Midnight Oil, “Bells and Horns in the Back of Beyond”)

Lord, we know what we are, but know not what we may be.
(William Shakespeare, Hamlet 4.5)