A mistress is a man's long-term female lover and companion who is not married to him, especially used when the man is married to another woman. The relationship generally is stable and at least semi-permanent; however, the couple does not live together openly. Also the relationship is usually, but not always, secret. And there is the implication that a mistress may be "kept"—i.e., that the man is paying for some of the woman's living expenses. Historically, the term has denoted a kept woman, who was maintained in a comfortable (or even lavish) lifestyle by a wealthy man so that she will be available for his sexual pleasure. Such a woman could move between the roles of a mistress and a courtesan depending on her situation and environment. In modern times, however, the word mistress is used primarily to refer to the female lover of a man who is married to another woman; in the case of an unmarried man it is usual to speak of a "girlfriend" or "partner." Historically a man "kept" a mistress. As the term implies, he was responsible for her debts and provided for her in much the same way as he did his wife, although not legally bound to do so. In more recent times, it is more likely that the mistress has a job of her own, and is less, if at all, financially dependent on the man.
A mistress is not a prostitute: while a mistress, if "kept", may essentially be exchanging sex for money, the principal difference is that a mistress keeps herself exclusively reserved for one man, in much the same way as a wife, and there is not so much of a direct quid pro quo between the money and the sex act. There is also usually an emotional and possibly social relationship between a man and his mistress, whereas the relationship to a prostitute is predominantly sexual. It is also important that the "kept" status follows the establishment of a relationship of indefinite term as opposed to the agreement on price and terms established prior to any activity with a prostitute.
The historically best known and most researched mistresses are the royal mistresses of European monarchs, for example Diane de Poitiers, Barbara Villiers, Nell Gwyn and Madame de Pompadour. However, the keeping of a mistress in Europe was not confined to royalty and nobility but permeated down through the social ranks. Anyone who could afford a mistress could have one (or more), regardless of social position. A wealthy merchant or a young noble might have a kept woman. Being a mistress was typically an occupation for a younger woman who, if she was fortunate, might go on to marry her lover or another man of rank. The ballad The Three Ravens (published in 1611, but possibly older) extolls the loyal mistress of a slain knight, who buries her dead lover and then dies of the exertion, as she was in an advanced stage of pregnancy. It is noteworthy that the ballad-maker assigned this role to the knight's mistress ("leman" was the term common at the time) rather than to his wife.
In the courts of Europe, particularly Versailles and Whitehall in the 17th and 18th centuries, a mistress often wielded great power and influence. A king might hold numerous mistresses but have a single "favourite mistress" or "official mistress" (in French, "maîtresse en titre"), as with Louis XV and Madame de Pompadour. The mistresses of both Louis XV (especially Madame de Pompadour) and Charles II were often considered to exert great influence over their lovers, the relationships being open secrets. Other than wealthy merchants and kings, Alexander VI is but one example of a Pope who kept mistresses, in violation of the celibacy vows required by the Catholic church. While the extremely wealthy might keep a mistress for life (as George II of England did with "Mrs Howard"), even after they were no longer romantically linked, such was not the case for most kept women. In 1736, when George II was newly ascendant, Henry Fielding (in Pasquin) has his Lord Place say, "…but, miss, every one now keeps and is kept; there are no such things as marriages now-a-days, unless merely Smithfield contracts, and that for the support of families; but then the husband and wife both take into keeping within a fortnight."
During the 19th century, a time in which morals became more puritanical, the keeping of a mistress became more circumspect, but conversely the tightening of morality also created a greater desire for a man to have a mistress. When an upper class man married a woman of equal rank, as was the norm, it was likely that she had been strictly brought up to believe that sexual intercourse was firmly for procreation rather than recreation. Some men thus went to a mistress if they wanted a less prudish female companion.[citation needed]
It occasionally occurs that the mistress is in a superior position both financially and socially to her lover. Catherine the Great was known to have been the mistress of several men during her reign; however, like many powerful women of her era, in spite of being a widow free to marry, she chose not to share her power with a husband, preferring to maintain absolute power alone. In literature, D. H. Lawrence's work Lady Chatterley's Lover portrays a situation where a woman becomes the mistress of her husband's gamekeeper. Until recently, a woman's taking a lover socially inferior to herself was considered much more shocking than the reverse situation.
20th century
During the 20th century, as many women became better educated and more able to support themselves, fewer women found satisfaction in the position of being a mistress and were more likely to pursue relationships with unmarried men. Since divorce became more socially acceptable, it was now easier for men to divorce their wives and marry the women who, in earlier eras, would have been their mistresses. However, the practice of having a mistress still existed among some married men, especially the wealthy. In Europe, for example, many cultures continued to acknowledge and condone the practice of keeping mistresses.