What does the Bible say about living together?

Question from April:
Can you tell me where it talks about living together before marriage? Not sex. Just living together? We are talking with my son this weekend and we can't find it. Thank you ;)

Answer from Pastor Bob:
Well, I don't know any couples living together who aren't also having sex. But the sin is the sexual immorality before marriage. Hebrews 13:4 says, "Marriage must be respected by all, and the marriage bed kept undefiled."
If a couple were in the same household under the supervision of parents, it might be different, although just sleeping in the same house puts them in a very tempting situation.
The other problem with living together, is that even if a couple was not sexually active, everybody would assume they were, and Ephesians 5:3 says that there should not even be a "hint" of sexually immorality among you. So it harms their Christian testimony.
In addition to the Biblical reasons, there are psychological and social reasons why cohabitation is a bad idea. Couples think they are "trying out" marriage by living together, but it is impossible to "try out" marriage, because marriage is a commitment, and there is no commitment to living together. Either party can leave at any time, so it is not really a test of marriage. And studies show that people who live together before marriage are 50% more likely to get divorced than those who do not. Why is this? Well, if they don't respect the bonds of marriage before marriage, why should they respect the bonds of marriage after they are married?