More than 150 women who have had extramarital affairs were interviewed by Seton Hall University (South Orange, N.J.) associate professor of sociology Lynn Atwater, author of The Extra-Marital Connection: Sex, Intimacy and Identity (Irvington Publishers, 1984, $9.95).. According to Atwater: "It is our culture which pushes people into affairs. We've had a rising revolution of expectations for marriage generally. It may very well be higher than can be met." Television is one factor contributing to extramarital affairs. "Shows like 'Dynasty' fuel a level for excitement," triggering dissatisfaction. "People question their own life styles, asking, 'Why am I settling for this?' " "Half of all people are having affairs at some point in their married lives, which says something about the kind of society we are living in, too, not just about individual people." We lack patterns for cross-sex friendship. "I recommend extramarital friendships as a way to support a marriage. It's a mistake to try and close everything off so tightly. "You have to work at keeping your marriage monogamous every day. It is ridiculous to say, 'We couldn't help ourselves' or, 'Before we knew it, it happened.' " "People need both security and newness, stability and change. We've got a fine balancing act here to pull off."