Cohabitation is an arrangement where two people who are not married live together. They often involve a romantic or sexually intimate relationship on a long-term or permanent basis. Wikipedia
Today, cohabitation is a common pattern among people in the Western world.
In Europe, the Scandinavian countries have been the first to start this leading trend, although many countries have since followed. Mediterranean Europe has traditionally been very conservative, with religion playing a strong role. Until the mid-1990s, cohabitation levels remained low in this region, but have since increased.
During the past decades, in Western countries, there has been an increase in unmarried couples cohabiting. Historically, many Western countries have been influenced by Christian doctrines on sex, which opposes unmarried cohabitation. As social mores have changed, such beliefs have become less widely held by the population and some Christian denominations today view cohabitation as a precursor to marriage. Pope Francis has married a cohabiting couple who had children, while former Archbishop of Canterbury Rowan Williams and the Archbishop of York John Sentamu have expressed tolerance of cohabitation.