It depends on the man and his view of marriage.
Sometimes having seen how things went with his parents, loved ones, and friends can effect his outlook.
For every reason one guy gets married is a reason why another guy won't. Someone once said, "Don't marry the person you can live with. Only marry the person you can't imagine living without."
Bottom line is there are no magic spells, engagment chicken dinners, certain amount of sex, living together. pregnacy, ultimatums...etc that will work on every guy.
However when you think about it why would a woman want to marry a guy who is not interested in marrying her?
No one should have to "sell or persuade" another person that you are "the one". This is something your mate should see for themself. At the very least every marriage should start off with BOTH people (wanting) to get married.
I recently wrote a hub stating "5 Reasons Why Men Should Not Get Married." They could just as easily apply to women.