a: Affairs. Dual career couples have so many responsibilities they have very little left over for themselves as a couple. When they met they were single, there were no children and they were focused on each other; that was then, and now they are pursuing careers, having children, running homes and there's not much left for themselves or each other. In the workplace there is the proximity of all kinds of other adults and many working relationships develop into affairs. It's a sign that their relationship is in difficulties. Couples have so many responsibilities they don't spend much time together in a personal way and they lose their direction in terms of continuing to develop their relationship and intimacy with each other. There's a growing distance between them.

q: What causes that distance?

a: After a couple gets together their relationship hits the power struggle stage. Their differences come forward and this is a natural development in their relationship. They can address it in a creative way, or fight, or let distance develop between them, have an affair or leave the relationship. It's a reflection of where we are as a society that we don't know how to deal with distance well. We have to learn to resolve our differences but often it is not something we've learned from our families so we have no legacy of how to deal with problems in a constructive or creative way. So a couple avoids each other, or they are defensive and there is no resolution. It may look as if things are going along as usual but they are not. When we've been close and invested a lot of time in someone, all kinds of fears come up in dealing with conflict. Some people go around it but deep down it's still there, it's just been put on hold. So distance grows and affairs start.

q: Is it mostly women or men having the affair?

a: It's approximately half and half. If the woman is working, she is as likely to have an affair as the man, but if she is home raising the children, it is most likely the man.

q: Is there a lot of guilt involved in the affair?

a: I don't think men think about it. They are driven. Women are much more aware of what they are doing but they are willing to risk their relationship for excitement. Everyone is looking for someone to be close to and if a woman is living with a man she is not emotionally close to, she'll look for someone else. It's a human trait. We're social animals.

q: What do most people get from an affair?

a: What they are not getting in their relationships. They get someone to pay attention to them, someone who is fun to be with, who likes them, who offers a respite from a life full of responsibilities. They get excitement and novelty; they feel alive.

q: So it isn't just sex?

a: Sex is a vehicle for a man to be close to a woman. If she's not interested in him and starts to pull back, the man won't be happy for very long. Women have other women to talk to, they are good at conversation and discussing things, but men don't react that way. Men are wired differently. If a woman is not interested in him sexually, the man takes it as a sign that the woman is not pleased with him. When a woman is exhausted she doesn't want to be sexual but men are more likely to want sex. They read other things around sex, for example - 'does this woman like me?' A lot of it is unconscious. A man will stay in that situation for a little while, but longer than a year? I don't think so. Men are very much at risk of having an affair if things are going badly in their sex lives.

q: When someone discovers their partner has been having an affair, does it usually lead to a break-up?

a: Because of the deception involved, people lose faith in one another. Even if they find out about the affair two years later, they feel betrayed. Even if the guilty partner is just going to the store for milk, the other feels anxiety and fear. They want to trust that person, but they feel they can't.

q: At what age are most people likely to have an affair?

a: In their early 40s for both men and women.

q: Do some people have many affairs within a relationship?

a: There's a pattern. There is a seven-year cycle. We used to laugh at the idea the cycle was biologically driven, but it is. Men and women develop a relationship, set up a life, have a couple of children, stay for a few years and then there's an end of sexual attraction between these two people. What is the glue that holds them together if their relationship has been mainly physical and having children together? The only thing that will keep them together is a real friendship - if they really like each other, if they are much like each other's best friend. That will carry them beyond those first few years, if not, the relationship will dissolve.

q: Do you think this is a trend?

a: I think we'll see more and more people going in and out of relationships every few years, about every five to seven years. Ten is stretching it. They learn things from the relationship and move on. The issue is children. The blended family is going to become the norm, and it becomes very complicated. It adds layers of difficulties. It can be positive but it depends on how people deal with conflict.

q: Can counseling help?

a: After one partner has had an affair, a couple have to learn to trust each other again. Very few couples can do it alone because of all the feelings unleashed and their lack of skill in dealing with conflict. Conflict can erode any relationship.

q: We sometimes hear of an affair being a positive experience. Do you agree?

a: An affair is a red flag, a sign that a couple is experiencing crisis. It can be a real opportunity, however, to develop their relationship in a different direction, if they are willing to do that. Some people focus only on the affair and not what led up to it. They are angry, they feel they have been wronged and they go there with a vengeance. They have to think where were we with one another beforehand? There are different kinds of affairs. Now people meet through the Internet and they may sexualize the relationship, it can become physical. Of course, sometimes people embark upon an affair because they feel unhappy with themselves, they feel inadequate in life and it's not a relationship issue.