The most important reason for adultery is that both men and women have different priorities even after their marriage. The inability to resist temptation. Women's priorities are almost exactly in reverse order. They want romance back in their lives. They want exciting sex.
Affairs are very exciting but they can also bring in an enormous amount of hurt and devastation.
It is also important to remember that,even though it may be very painful, marriages can and do survive affairs. It was based on love, equality, sexual attraction and friendship, rather than security,status and the opportunity to leave home and start your own family. Women were expecting more from marriage,and if their expectations were raised, it would also mean that if they were not met, she would more likely look outside marriage for sexual or emotional fulfilment. In olden times many women who married were virgins, the majority of people still disapprove of sex before marriage. Only a few men and women had sex with someone other than their spouse when they married.