Complex sentence: For an unmarried woman, the utmost importance is placed on virginity before marriage, and "proof of virginity" in the form of bloodstains on a bed sheet is required in some cultures to proudly demonstrate after the wedding night.
Split into simpler sentences: For an unmarried woman, the utmost importance is placed on virginity before marriage. There is a requirement in some cultures for "proof of virginity" (in the form of bloodstains on a bed sheet) to be proudly displayed after the wedding night.