Sex isn't the same as intimacy. Without a doubt, it can be an element of closeness. However, sex does not imply intimacy. It comes with no assurance of closeness. Intimacy does not require sexual activity. Yet, in modern popular culture, practically every reference to closeness is a reference to sex.
To genuinely feel intimacy, we must first get past the teenage assumption that sex and intimacy are interchangeable. One thing that a person cannot live happy without is intimacy. Consider this. Who do you know who is the happiest, who is actually flourishing? Is it simply sex or do they have intimacy as well? Isn't it true that they have intimacy? They may have sex, but a true experience of closeness is at the heart of their existence.
They can share their lives with other people. They genuinely care about the individuals they interact with. They get along well. We can live happily without new cars and expensive clothes; we can live and thrive without our dream homes; we can vacation in all the right places—but we cannot live happily without closeness.
One of our basic desires and a requirement for happiness is intimacy. You can live without closeness, but you won't be happy. Human humans crave closeness above all else. We all want happiness, yet we often mix it with a desire for pleasure and material stuff. But once we've had our fill of pleasure or acquired our desired items, we're still left wanting. What are you looking for? Intimacy.
In the end, our quest for happiness is a yearning for intimacy. We can live without a lot and still be happy if we have intimacy. All the wealth in the world won't satisfy our hungry hearts if we don't have closeness. Our hearts stay restless, impatient, and dissatisfied until we experience closeness.