Go to your local auto parts store and get the 3M Super weather strip adhesive. The BLACK not the yellow. Put a sufficient quanity of it in there to spread all around, then press the two halves together. NOW pull it back apart and hold it open until the adhesive dries to the touch. THEN and only then, put the shoe on and walk on it. You'll never see it open again.
(unless you walk around in acetone, that is)
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