In just a few weeks’ time Pamela Anderson and I will be releasing our new co-authored book, Lust for Love: Rekindling Intimacy and Passion in Your Relationship. Already the media is commenting on the odd pairing of a world-famous sex symbol on the one hand, and an author and activist on the other.But Pamela is much more than just an author and an activist. She is a brilliantly insightful woman, especially about relationships (And yes, I hope my joke made you laugh. But who is to say that rabbis can’t be pinups? Perhaps in the next life.) Our main argument in the book is that marital passion is declining all round. Cynics like Thomas Webbe capture it best: “There is no heaven but women, nor no hell save marriage.” Or Zsa Zsa Gabor, who said: “A man in love is incomplete until he has married. Then he is finished.”Recent American census data shows that marriage may be on the way to the grave in the US. The published data says that the number of US adults who never marry has hit an all-time high of one in five. In 1960 it was one in 10.We’re lucky it’s only that high. In Scandinavia only 20% of the population bother to marry. In France and Britain it’s about a third.To many a single mind, marriage sucks. It’s a bore. Marriage is about “settling down.” The single years are a house on fire. The married years are about a kid vomiting on your suit and so many bills hitting you that you feel punch-drunk.As for sex, here we turn to Zsa Zsa Gabor again: “I know nothing about sex. I’ve always been married.” Passion and pleasure in all things, especially sex, is the goal of the age and most people are convinced that marriage just cannot provide it.At lectures across the world I ask women to raise their hands if they need a man. No hand goes up. Even from the married women. I follow up.Raise your hand if you need a refrigerator.All the hands go up. They chuckle.And then my conclusion: “Why do you acknowledge a dependency on a hunk of metal that will cool your milk rather than a piece of flesh that will warm you heart? Because GE brings good things to life!” Jewish tradition sees things differently. Adam, the first human, was a hybrid of male and female. When Adam fell asleep, God removed a tzela – often translated as “rib” but actually meaning “side” – the feminine side, from its person.The result was the compartmentalization of masculine and feminine, man and woman, with each being incomplete without the other. Ever since, each instinctively and erotically seeks unification with the lost half.This is the mystical reason why even in a secular age the ideal still remains marriage, with every Hollywood chick flick ending with a wedding. We don’t marry to obviate loneliness, because shacking up would afford the same degree of companionship. Rather, we marry so that two halves can be sewn together as an indivisible whole. He who separated us is He who can unite us.Humans intrinsically strive to achieve an ever-elusive wholeness, which can only be achieved through the spiritual union of marriage, which is why so many people who are not church-goers still want a church wedding.In its most romantic passage the Book of Genesis (2:24) expresses it thus: “Therefore shall a man leave his father and his mother, and shall cleave unto his wife, and they shall be one flesh.”Of all the benefits of marriage it is perhaps the sense of invincibility and invulnerability which is strongest.We men are sick of existing as “human doings,” always having to prove ourselves through productivity. We seek to become human beings, to be appreciated for our souls, our existence, our personhood. It is marriage, rather than career, which can provide that.Genesis describes Adam as having been lonely. But why? He was surrounded by angels! But angels are perfect. There was nothing Adam could contribute that they were missing. Loneliness ensues when we feel appreciated but not necessary, admired but not essential. It was only when God provided a vulnerable creature like Adam himself, Eve, that his loneliness was remedied.But there are many people who are married and still feel very lonely. The reason? People don’t want to be loved, but desired. Not appreciated, but lusted after. Marriage today is based on the Christian concept of love rather than the Jewish concept of lust. The New Testament condemns lust: “For everything in the world – the lust of the flesh, the lust of the eyes, and the pride of life – comes not from the Father but from the world” (1 John 2:16).St. Paul famously argued that “God is love” and that all marriages should be based on the comforts of compatibility, friendship and shared experience.Judaism believes that marriage must be built on deep desire and covetousness. The holiest book of the Bible, the Song of Solomon, is an erotic poem that describes the burning yearning between a man and a woman: “Your breasts are like two fawns, like twin fawns of a gazelle that browse among the lilies” (4:5).The Tenth Commandment is clear: “Thou shalt not covet thy neighbor’s wife” – which means you should be coveting your own.Lust is, quite simply, much stronger than love.How do we recapture it? By focusing on the three rules of erotic lust.The first is frustrated desire; erotic obstacles.Lust is enhanced through an inability to attain the object of your longing, the failure to satiate human yearning. It’s the reason why Plato argued for unconsummated, “platonic” relationships, so that desire would never wane. And it’s the reason the Torah makes a wife sexually unavailable to her husband for 12 days out of every month (laws of Niddah).The second law of lust is mystery. Lust is enhanced in darkness and shadow. Ironically, the more the body is covered the more one lusts after it.The third law of erotic lust is sinfulness. The forbidden is erotic.A cursory glance at world classics demonstrates that it is not the righteous, loyal wife who fires the literary imagination but the unfaithful, sinful wife, like Anna Karenina, Madame Bovary, Tess and Lady Chatterley.To be sure, adultery is the most painful transgression of marriage. But now you know why the Torah made a wife sexually forbidden to her husband for a portion of every month, thereby injecting erotic sinfulness into a relationship.The many who complain that religion creates sexual taboos in relationships forget that such taboos can often enhance lust, while a permissive society that makes sex constantly available turns it from chocolate to vanilla.Unlike the “love marriage,” which is based on closeness and constant intimacy, the “lust marriage” is based on separation, renewal, and a measure of distance. All great advice from a religion that champions lust over love in marriage.The author, “America’s rabbi,” is one of the world’s most celebrated relationships experts and is the international best-selling author of 31 books. His national TV show, Shalom in the Home, won the National Fatherhood Award. Follow him on Twitter @RabbiShmuley.