How to explain a best friend break up to a 7-year-old?

Photo by Allen Taylor on Unsplash

My son (7) has been best friends with another little boy (also 7) about as far back as he can remember. They met in preschool.

That is where I met the little boy's mom. We became “acquaintance friends”. We noticed our sons gravitated toward one another so we began arranging playdates, which we had on a regular basis for many years.