Not that I personally am of the "violence is justifiable" camp, nor have I met feminists who are. But in theory I could understand the mentality - not due to punishment being justifiable for the behavior regardless of who is cheating, but because that double standard ruins women's lives if they are the ones cheating. Women's careers usually get complete gutted over sexual scandals and infidelity, and are often harassed or treated as damaged goods if they are the victims of a cheating spouse, while the same doesn't usually apply to men.

That doesn't make physical violence justified, of course. But the double-standard is incredibly unfair and in many ways creates violence against women. Of course, I think the better course of action is to call it out and illuminate the issue... But that doesn't necessarily change things on a societal level :/

In the case of people who are public figureheads, I think it can get further complicated because a lot of people can be in business relationships (e.g. may be told to appear to be in a relationship for the press), or may have other arrangements that are okay with each other but not exactly popular relationship options. If a famous couple announced they were polyamorous or in an open relationship, that would probably be seen as scandalous in and of itself. But even in those cases, God help you if you're a woman perceived as cheating on a man, because you may as well kiss your career goodbye.