February 13 has gained notoriety as the Day of the Unfaithful, a response to the traditional celebration of love on Valentine's Day, which occurs the following day. This unofficial event, also known as 'Mistress Day' or 'Galentine’s Day,' was initiated in the United States and has been promoted through social media and dating applications. It caters to those in extramarital affairs or seeking relationships outside of their commitments, providing them with their own reason to celebrate, albeit controversially.

The origins of the Day of the Unfaithful can be traced back to the rising acceptance of infidelity in certain social circles, particularly through platforms that allow married individuals to connect with others. The day has sparked significant curiosity and debate, especially due to its proximity to the well-established romantic holiday of Valentine's Day. Critics point out that it glorifies cheating, while proponents argue it recognizes the complexity of modern relationships.

In recent years, the celebration has grown in visibility, evolving from a niche observance into one that is discussed broadly online and within popular culture. As it continues to gain traction, there are implications for societal views on marriage and fidelity, prompting discussions about loyalty and the evolving definitions of love and commitment in contemporary society.