It's not surprising, but it's not logically inevitable.
Suppose every couple divorced exactly on their 50th anniversary if they were both still alive. Then a couple that has been married 49 years is almost certain to divorce, whereas a newly married couple has a reasonable chance of dying first.
Suppose every couple divorced exactly on their 50th anniversary if they were both still alive. Then a couple that has been married 49 years is almost certain to divorce, whereas a newly married couple has a reasonable chance of dying first.