Sex means you aprove of each other

But how deep that approval may be varies considerably. 

My mother and father did not love each other very much. and considered that normal. They went to church instead. 

When I worked in Silicon Valley in the Nineties, the Computer employees were sexually active,  extremely so. And considered this part of their approval of their profession, and were quite put out if you did not have sex with them.

It is well-known that Cleopatra had sex with Julius Ceaser and bore him several children. How these children of complicated parentage managed this is not known, but there were plenty of them.