seal one's fate
Decide what will become of one, as in The letter of rejection sealed his fate; he'd have to apply to other medical schools. This term employs seal in the sense of “permanently fix or fasten something,” a usage dating from the mid-1600s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.