That’s the way the mop flops

that's the way the mop flops

There is nothing we can do about the way things have unfolded, especially bad ones, so there is no reason to be upset about it. (A variant of the more common "That's the way the cookie crumbles.") I'm pretty gutted about not getting into the grad school program I wanted, but hey, that's just the way the mop flops.
See also: flops, mop, way
Farlex Dictionary of Idioms.

That’s the way the mop flops

sent. This is the way things happen.; This is typical of a random pattern of events. (Contrived.) Sorry to hear about that, but that’s the way the mop flops.
See also: flops, mop, way
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • That’s the way the cookie crumbles
  • that's how the cookie crumbles
  • that's how the mop flops
  • that's the way the cookie crumbles
  • that's the way the mop flops
  • the way the cookie crumbles
  • That’s the way the ball bounces
  • that's the way the ball bounces
  • that's how the ball bounces
  • that's the breaks