It is what it is.

'It is what it is' is an expression someone will say when someone else has complained about a situation, and the person realizes that there's nothing they can do to change it. By saying this, they're trying to get the person who complained to realize it.

Example:
-I wish they weren't such micro-managers. It drives me crazy.
-It is what it is. I doubt they're going to change at this point.