text: Sexual relationships There are a wide variety of factors that influence sexual relationships during emerging adulthood; this includes beliefs about certain sexual behaviors and marriage. For example, among emerging adults in the United States, it is common for oral sex to not be considered "real sex." In the 1950s and 1960s, about 75% of people between the ages of 20–24 engaged in premarital sex. Today, that number is 90%. Unintended pregnancy and sexually transmitted infections and diseases (STIs/STDs) are a central issue. As individuals move through emerging adulthood, they are more likely to engage in monogamous sexual relationships and practice safe sex.
  Across most OECD (Organisation for Economic Co-operation and Development) countries, marriage rates are falling, the age at first marriage is rising, and cohabitation among unmarried couples is increasing. The Western European marriage pattern has traditionally been characterized by marriage in the mid-twenties, especially for women, with a generally small age difference between the spouses, a significant proportion of women who remain unmarried, and the establishment of a neolocal household after the couple has married.
  Housing affordability has been linked to home ownership rates, and demographic researchers have argued for a link between the rising age at first marriage and the rising age of first home ownership.