Our religion is never based on people's opinions or culture but on clear orders from Allah which came in Quran as explained by the prophet Muhammad (peace be upon him and his holy progeny0. Our scholars never state any act as forbidden or permitted or recommended or disliked or obligatory without very clear evidence from Quran, Sunnah, Aql or Ijma'a (consensus). Sexual relationships without marriage is no exception as Allah in Quran said about the pious believers '' And those who guard their chastity (i.e private parts, from illegal sexual acts).Except from their wives. Sura  70 Aya 29. Social and cultural factors differ in different countries and different times, while the Islamic rules are always unified as code of conduct for humans everywhere and every time.

Wassalam