A lot here depends on what you think about marriage. If you exegete the first two chapters of Genesis you get a strong message concerning marriage. Specifically, everything God created was good. After man was joined with woman, it was very good. Man to be alone is not good.
The Hebrew for helpmate (the job for which a woman is created) literally means to stand before face-to-face. The sense is of completion, the joining together of the two into one. The point here is that God created us for marriage, and it is in that union where we find completeness. Marriage is the crown of God's creation.
If you are not of the Christian faith, then maybe you should look at the statistics concerning divorce among those who have previously lived together. Their divorce rate is three times higher than those who do not live together. The percentage of people who co-habitat and stay together for life is statistically zero.
If your goal is to play house, without concern for a lifetime together, then you lose nothing by living together. If you want to be with one person for life, then choose that person carefully, take things in the proper order, and be committed to a covenant relationship with that person.