There are thousands and thousands of people in the uk that have been missing longer than this.
How many of the thousands and thousands who are missing have gone missing in circumstances like these? Where they have a stable home life and are in education or who work. Who don't have any record of mental health problems or drug/alcohol abuse. Who were living a life where they were making plans, seeing friends, doing things with their families etc.
Most missing people are missing for short time before they turn up and there is usually a catalyst as well as ongoing issues.