Have you seen the movie Timer?
At puberty, or whenever they feel like it, everyone in the world(the first world) get's a heart clock installed. A heart clock is a timer counting down to the exact moment you fall in love with your soulmate. (It's a digital read out on your wrist.) The hero of our story, played by the magnificent Emma Caulfield, has her heart clock installed on her 13th birthday, looks at the number and is distressed to discover that "she" has to wait another 25 years until she meets the man of her dreams, which is UNACCEPTABLE! This woman goes on a quest to scew fate and fall in love hopelessly and truelly and honestly decades before her inconsiderately rude timer clocks out.
Her loneliness had an expiry date which was without pity.
(Emma has been in my mind for 14 years and I still swoon.)