Rapunzel.

Books SurLaLune publishing has a heavily annotated edition of Grimm's Rapunzel which includes details of sources, later updates and literary criticism. Here it is the on the implications of the marriage:

"On one level, this story is entirely about procreation and life cycles. The tale begins with one couple, man and wife, and ends by bringing another couple together to marry and have more children. In earlier versions of the tale, the prince doesn't always ask for Rapunzel's hand in marriage although a sexual relationship is implied when Rapunzel gives birth to twins near the end of the story."