go behind somebody's back

You went behind my back and took her away from me.

What I care about is that you went behind my back.

She goes behind his back in order to increase her final output.

None of us need ever go behind my father's back.

The women try to go behind his back to the doctor.

Richard's free hand went behind his back; a moment later, she saw the gun.

"And she would never have gone behind my back to do so."

It was enough that she had to go behind his back.

"You had no right going behind my back to him without ever saying a word to me."

What I'd like to know is why you had to go behind my back to box me in.