In contemporary western society, the Double Standard isn't as strong as it used to be, thanks to birth control, paternity testing, changing attitudes about the role of women and the role of marriage, and to advances in technology that allow women to support themselves outside of the home, making the landing of a husband no where near as essential to a woman's survival as it used to be. It still remains very strong in most Eastern societies, although not as much in highly Westernized ones like Japan or The Philippines. A century ago there was a consensus, enforced by law, that it's okay for men but not for women to fool around, with a strong social division between good women to marry and bad women to use as toys. No word on how it's possible for a man in this system to fool around without getting a woman in trouble. Most people nowadays tend to disapprove of cheating itself, regardless of the gender of the one who cheats (and, contrary to popular opinion, cheating itself is in fact less tolerated, see philosopher Alain de Botton). Note that there is a difference between cheating and the concept of polyamory, in that the latter assumes sincere, honest commitment (the associated concept of "polifidelity"), whereas the former implies a betrayal of the partner's trust.
Analysis / My Girl Is Not a Slut