Even a good marriage leaves people with longings for certain things their marriage will never be. So, do they accept that, make compromises, and say, "You can't have everything in life," which is what we always did? Or do they say, "I deserve more. I want to experience that thing and, you know, I have fifty more years to live than I used to." It's not necessarily that we have more desires today, but we do feel more entitled to pursue them. We live in this "right to happiness" culture, and yes, we do live half a century longer than we used to.

On some level we trade passion for security, that's trading one illusion for another. It's a matter of degree. We can't live in constant fear, but we can't live without any. The fear of loss is essential to love.

The secret to desire in a long-term relationship

If a woman isn't feeling sexual with herself, she won't respond to advances from any partner, male or female. When this woman goes dancing, she's finding a connection with her own erotic self. It might be about being on a dance floor, feeling free, not having to feel at all responsible for anybody else's well-being. For other people, it might be about going on a hike for four days by herself and reconnecting with nature and strength and endurance and beauty.

The very ingredients that nurture love - mutuality, reciprocity, protection, worry, responsibility for the other - are sometimes the very ingredients that stifle desire.

For some people, a one-night stand doesn't make any difference in a seven-year love affair. I don't believe the degree of betrayal is always commensurate with the egregiousness of the behavior. They are two separate things.

To look at infidelity from the point of view of sex is a complete narrowing of the phenomenon. There's a reason that the commandment is repeated twice in the Bible - once for doing it and once for thinking about it. We have always created structures and broken structures. It is essential to the human spirit.