Changes in sexual mores resulting from the lesser practical importance of marriage in a radically commercialized and bureaucratized society make the situation described in the last post quite a bit worse.
In such a society there is a tendency to delay or forgo marriage but not sexual activity. The result is that women become much less likely to bond permanently. (Also see this more detailed discussion.) The statistics I’ve seen don’t cover the effects of men’s sexual activity, but it seems believable that prior relationships would affect marital stability more in the case of women. As suggested by previous discussions, men are more interested in resolving an issue and going on to something else, women in fine-tuning personal situations, so the habit of choosing and changing would affect them more. Also, women are usually the ones who initiate divorce, which suggests that feminine failure to form stable bonds is a special issue.
As things are, the typical young woman has several sexual alliances without any expectation that the connection will be permanent. That means they give themselves without giving themselves, and to do so must fend off their own tendency to bond sexually. Anecdote and personal experience suggest that the result is to make them narcissistic, disloyal, mindlessly willful, indifferent to the actual well-being of the man, and so on. So the situation exacerbates tendencies already implicit in the present radically impersonal form of society.
Sexual looseness (together with feminism) also deprive young men of a strong motive for getting their acts together. They no longer have wife and family as a definite goal with a definite form to aspire to. It’s not necessary for the sake of satisfying immediate impulse, and the girls have all been told not to cooperate with the scheme on the grounds that a definite form for anything other than career and formal education means oppression. Marriage and family have been institutions which most men could participate in and lead. Egalitarian marriage, in which everything is equal and subject to constant negotiation, eliminates the incentive.
So all in all the sexual aspects of the present situation radically reduce the value of men and women as mates, and radically reduce the appeal of forming a permanent connection. Without permanent connections you get distrust and consequent fault-finding, and the response of each sex to the other increasingly becomes “who wants one of them?”
An additional problem is that marriage requires discipline on both sides, and people usually don’t just decide to be disciplined. So making marriage one choice among others is a problem. Charles Murray tells us that for the top 20% the discipline is provided by careerism and rational self-interest, but that motive can’t be effective with everyone since not everyone can have what you’d call a career and most people are more inclined to go with the flow than calculate ways of maximizing future payoff. And indeed Murray tells us that marriage has pretty much collapsed among less successful people.