It is simpler. In a nutshell, the only way you can change outcomes of human behavior is by changing the environment that it occurs in. Outcomes aren't arbitrary though, and they can't be dictated.
People don't change their behavior in a vacuum, they react to their environment. Women demanding that men marry them in the current environment means that men won't enter any kind of committed relationship, not that they'll just give in and get married in a grossly pathological environment. Given these two options, women choose the committed relationship in the absence of marriage. If you want to change the choices, you have to change the environment they are made in.