"So, the way I was taught this was, there are two ways a society can be, and in both of them if you try to live like you're in the other society it won't work, so they're ways societies can be, rather than ways that individuals can be, and there's not much point in thinking less of individuals for being the way that succeeds in their society.
But - in Osirion there's no divorce, except very rarely for adultery, which means that if you don't betray your husband he can never stop supporting you, ever, no matter what, and supporting you at the cost of his own comfort if his income falls. Why would a man agree to that? Because in Osirion it is the only way for him to have a woman; no one of anywhere near his background or standing would ever consider a relationship with him if he won't marry her, and even if she would her relatives will step in and forbid it. He can pay people, if all he wants is sex, but that's not all men want and a woman's love, a homemaker, a mother for their children, they can only have in marriage.
Because that's how things work, women want marriage, and are willing to work to maintain their reputation and avoid compromising situations and exercise good judgment until they're married, and women who can't do that don't get married, or don't have very good options anyway, so no woman wants to stop abiding by the norms of her society. And so there's no benefit, for either men or women, to behaving badly, which is what it takes to get people to behave well.
In Avistan - I was told, and I know parts of this are true some places but I don't know anything about Cheliax and I don't intend an insult - women will sleep with men outside of marriage, and in many places kill their children if any result. And who would promise to support someone all their life, with no way out, if instead they could be careless with affection and see whoever they please and change their mind once a week? Some men, to be sure, but not all of them. So those countries weaken marriage, to make it something men will agree to. They permit divorce for all kinds of reasons, or for none, or they just don't frown that much if a man abandons his wife and stops supporting her. But then why would a woman guard her virtue and her reputation and wait many painful years for a marriage that's only half a promise anyway? They mostly don't. And so there's no benefit to behaving well, and so very many of them behave badly."