Entering the Protestant Reformation, around the 1500s, beliefs on procreation and gender roles began to loosen up. Society became more comfortable with sex occurring for reasons other than procreation, but only if it was within a marriage (Crooks & Baur, 2011).
However, it was the Enlightenment era that really helped advance these beliefs in a progressive manner (Crooks & Baur, 2011). Around the 1700s, people started to question things with reason, due to notion of scientific rationalism. They wanted to know why our culture had these stricts beliefs on sex and gender. They wanted the evidence to support these beliefs that had been passed on throughout time. Of course though, there were no reasons to be found, and rather they found that the answers to their questions were more subjective (Crooks & Baur, 2011).
The artwork above, Newton by William Blake, illustrates how during the Enlightenment, philosophical ideas were being questioned by science and reasoning (http://www.martinfrost.ws/htmlfiles/enlightenment_age.html).