A funny thing happened at the gym one day.
I greeted the people I'd met before, asking about their weekend plans. A woman on the elliptical machine started reading off her weekend schedule that revolved around school sports for her children. She didn't exactly say she had no free time, but she said: "If you have children who are in school sports, every season your friends are chosen for you." She went on to describe the life of a sideline parent.
What does "your friends are chosen for you" mean? Chance or circumstance has thrown you together. Going back to the gym analogy, if you see someone you would rather not spend time with, you can avoid them by working out in another part of the gym. But in some situations, you are put together and it's impractical to escape.