just one of those things

A random occurrence that can't be explained. For example, It wasn't their fault that the show failed; it was just one of those things. This expression was given greater currency as the title and refrain of one of Cole Porter's most popular songs (“Just One of Those Things,” 1935). [c. 1930] Also see one of those days.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.