When Kate's youngest child left for college, she had mixed emotions. She was excited for her son but sad about the loss of her daily kid-focused routine. Those feelings didn't surprise her -- she'd heard all about empty-nest syndrome from her friends -- though she was shocked to learn that her husband felt just as sad and alone as she did. "We started talking," Kate told me," and pretty soon we realized we're in this together. It actually made us closer." One night Jim came home with a bottle of wine and a pizza, and he and Kate enjoyed a picnic in their den instead of dinner at the table -- because they could. And then they had sex in the kitchen -- because they could.Kate and Jim, like so many other couples I see in my counseling practice, successfully moved past the loss of one part of their life together into a new -- and sexy phase. Of course not every couple navigates the empty nest so easily. Having the house to yourselves can be tough at first; in fact, it's a common trigger for divorce, because many couples realize they have little left in common except parenthood. But marital satisfaction may in fact improve once kids take flight: women's marital satisfaction tends to increase after their children have left home, according to a study in the November 2008 issue of Psychological Science. That's not just because they have more free time; it's also because they enjoy their partner more.Even if you're struggling to adjust, a newly empty nest presents an opportunity to reconnect with your partner, rediscover your relationship, and reinvigorate your sex life. Here's how.Remember where it startedThink back to the early days of your relationship. What attracted you to each other? Was it his sense of humor? Her adventurous side? Two of my clients made a game out of getting reacquainted. "We took separate cars to a bar where we pretended we didn't know each other," said Peter. They started talking, Peter bought drinks -- and they went home together. Research supports this tactic: Long-time couples can rekindle romance by acting like strangers on a first date, a recent study at the University of British Columbia showed.Make allowancesEven if you're in great shape, your bodies are different now -- and so, likely, is your stamina. Can't swing from the chandelier the way you used to? Adjust. My client Sarah, for example, has a bad back and finds the missionary position painful. Instead, she and her husband enjoy sex while lying side by side or spooning. Think in terms of what you can do sexually, not what you can't.Embrace the differencesSex isn't what it was 20 years ago. That doesn't mean it's worse. Celebrate what improves with age: Younger men may have stonger erections, but older guys tend to have better control. You both know each other's bodies, you've perfected your bedroom technique, and you may feel less inhibited than you did in the past.Stoke the flamesAs we age, it's not unusual for our libidos to decrease a bit. But in my experience, the second honeymoon created by an empty nest may actually boost sex drive. Give your desire a push by talking about your fantasies or watching a sexy movie together. Even a simple compliment can help get your partner in the mood. Remember, communication is key to a hot sex life.Invest in yourselfWhen kids leave home, the parent more involved in caring for them often loses part of his or her identity. As a result, partners may find each other dull. So inject some thrill into your life -- and your relationship -- by pursuing new interest. Volunteer, get a hobby, or write up your dream "To do" list and start crossing things off. A stimulating life outside the bedroom will nurture a stimulating life inside it.An empty nest doesn't have to equal an empty life. If you see this time as an opportunity, your relationship -- and your sex life -- can thrive.