that's (just) how it goes

There is nothing we can do to change or prevent the way things have unfolded or will unfold; this is just the normal way things happen. Usually said of negative events or outcomes that are or seem unfair. A: "So you mean after nearly a year of hard work, all my profits are going to taxes? That's bull!" B: "Yep, but that's how it goes." A: "I can't believe their little boy died of cancer." B: "I know, it's really awful. That's just how it goes sometimes."