Why okay for wives, but not for husbands?

Why is it perfectly okay, natural, and somewhat of an actual TURN ON for a wife to have a vibrator, to appreciate & enjoy , and to pleasure herself freely and regularly when her husband isn't around? Yet when a husband gets caught masturbating to online late at night then suddenly he is some sort of an "unappreciate pig" who has a "serious addiction that requires counceling"? Shouldn't what's good for the Goose be good for the Gander?