This very popular saying is unfortunately wrongly taught and so it continues to get passed down with a mistaken explanation. The mistaken explanation is that 'love' and 'war' are two equal things that anything can be done during and it not be considered wrong. THAT IS A FALSE DEFINITION. But understandably so,with how the quote is phrased-its very easy to see how it's been misunderstood.THIS IS THE REAL DEFINITION....'All is fair in love and war' actually means this.... During war, two people who are romntically involved go through many ups and downs. It's a terrible heartbreaking experience for both. It's an emotional rollercoaster filled with sadness,pain,anger and both stress and distress. So during this time if one or both parties decide to have an affair whether it be ongoing or just once....this is considered "fair"....because during this time of extreme pain-the distance and time apart can be almost unbearable and the need for human contact and the desire for human touch is something that everyone involved feels can be overlooked if it happens only during this time of war. The danger involved during war is so scary and brings so many emotions out that it's human narure to need someone else to "lean" on and that often leads to more. So "All is fair in love and war" actually means that an affair during combat can be overlooked and is considered both fair and forgiveable.
She longed for her husband and feared for his life. She spent the night with another man to comfort her, and kept repeating to herself...'all is fair in love and war'.