I think in many places, especially rural communities, it was normal for couples to "walk out" until there was a pregnancy, and then they would marry!
People had a very pragmatic attitude to life: they would want to have children and it was necessary for the survival of the community, so they would make sure they were with a fertile partner. And if nothing happened, they might call it a day and go see if they would "catch" with someone else.
Eventually the Victorian "moral" attitudes percolated down though, and these remained with us until fairly recently.