Of course sexual activity was expected. Sex was made enjoyable and beautiful in its God ordained proper context - marriage.
Wait- are you implying that before Adam and Eve ate of the tree of knowledge, they only performed sex after being married? Please explain what marriage was back then, before man had knowledge. Who sanctioned the ceremony, God? Where exactly does God say "Only have sex after you go through this long and complicated ceremony" ?
I'm actually curious, is there a passage like this anywhere in the Bible?