That's probably the case, but what bugs me about it is that it's not at all alien. Although things have become more egalitarian in recent times in at least some cultures, a great many human cultures over the centuries have had just such a double standard, that it was okay for men to sleep with as many paramours and prostitutes as they wanted but unacceptable for women to sleep with anyone but their husbands.
Of course, there is a practical reason for this imbalance in a society with patrilineal inheritance, since men in such a society need to know that the children their wives give birth to are actually their own legitimate heirs, entitled to inherit their property and titles and whatnot and preserve the family legacy. Men can sleep around all they want and still know that any offspring their wives and concubines pop out are their own, so long as they can be sure their wives and concubines aren't sleeping around too.
Of course, by that logic, there's no practical reason why a man in a patrilineal society should be troubled if his wife sleeps with another woman, since there's no reproductive impact there. But then, while such customs may arise for practical reasons, they tend to accrete more emotional and moralistic rationales. A man in that culture might feel that a failure to control his wife's sexual activities was a humiliation regardless of who her partner was.