Men need "chase space" to fall in love. They need to be inspired by a woman who is high maintenance in the love department. If you become his undocumented wife, housekeeper, lover, companion and friend, and share the finances for the apartment,food and entertainment, he won't be able to chase you nor will he be willing to marry you easily, because he knows too much about you. Why should he marry you when he doesn't really have to?

If a woman requires a man to make a commitment before sex, to a long term goal of marriage and monogamy, she may lose the guy who only wants sex, but she will not lose a man who wants to marry. If a woman requires at least an engagement ring and a wedding date before living with him, she may lose the man who wants a freebie loaner wife, but not the man who wants to marry.

Romance happens in the courtship phase. It's purpose is to build good positive memories on which a marriage can be built. If you live together, the natural problems which will emerge, will disallow romantic fantasies which are so important. Not enough day dreaming time and too much problem solving can make a relationship a business deal rather than an exchange of respect for cherishing.

In the western world, where marriages are romantically based rather than "arranged", living together is statistically not a good way to begin or build a romance leading to a good marriage.