What is the male equivalent of a mistress?

The male equivalent of a mistress is often referred to as a "lover" or a "paramour." This individual is a man who is engaged in a romantic or sexual relationship with a woman who is already in a committed relationship with someone else, typically a husband or long-term partner.

Like mistresses, male lovers may provide emotional support, companionship, and intimacy to the woman they are involved with, while also potentially destabilizing or complicating her primary relationship. The dynamic between a man and a woman in this type of relationship can vary greatly, with some male lovers providing financial support, gifts, or other material benefits to the woman they are involved with.

In some societies and cultures, male lovers may be more socially accepted or even expected, particularly in cases where the primary relationship is unhappy or emotionally distant. However, in many cases, the presence of a male lover can cause significant strain and conflict within the primary relationship, leading to jealousy, betrayal, and hurt feelings on all sides.