Double standard

Refers mainly to sexual double standards. Valid - in different forms - in almost all periods of British culture.

In the 17th and 18th centuries, it was common for members of the upper class, to have a wife and one or several mistresses. Marriage was official and could be presented to the other members of society. Upper-class marriages in the 17th Century were also often a matter of wealth, status or heritage/succession and did not happen out of love. Due to this, a lot of men did have mistresses from the lower class for pleasure.

With regard to sex, it was expected of women to be virginal and chaste, while it was common for the men to have a lot of experience due to them having mistresses.

Sources

http://www.socialpc.com/SocialIssues/Love-And-Marriage-In-The-18th-Century.html

http://historicalfictionauthorinterviews.blogspot.com/2007_06_01_archive.html