We joke about people being married to their jobs, but the numbers in my own life tell quite a tale. A typical workday sees me awake for 17 hours. I spend nine of those with co-workers. Since Jeff and I keep slightly different work schedules, I only see him for about five hours per weekday.
The jokes become less comfortable when you realize that you're spending more hours per day with your co-workers than you do with the person you married. Co-workers don't have the same commitment to permanence that spouses do; they are people you spend time with, but not people you share everything with. I marvel at how few people find this strange or unusual.